This is my pre-patch Awakener kill event tier list. This is also useful for those trying to get into Hardcore SSF for the first time and want to see how the Ascendancies stack up as they are right now. Of course this is subject to change with the new patch but I honestly think it won't differ that greatly.
The 5 top aspects that players will be looking for in this event are the following:
*How cheap it is to gear the builds in a class
*How damaging the build/class is to bosses
*How defensive the builds are
*Utility of the builds (stuff like autonomous skills like minions, mines/traps, totems)
*General speed of the build and class as far as clearing maps go
This is all factoring in minimal investment of course as it is SSF so we are looking at how well an Ascendancy performs with its builds with rare gears that you find just dropped around.
S Tier:
Necromancer: Without a doubt the best class in the game right now for HC SSF. Even if they substantially nerf Necromancer in the new patch, it will still be the best and has been a top choice for HC SSF for quite some time. Minions are powerful out of the gate with tons of single target damage and very cheap to gear. Their autonomous nature and high innate damage means you can spec your character for almost all defense and then kite around bosses while your minions do the work. I expect Necro to be the most popular class in this event. It's not the fastest class in the game as far as mapping goes but it makes up in other aspects quite handily. Can run just about every map mod as well which is big in SSF (don't really have to worry about reflect).
A Tier:
Occultist: Occultist specializes in damage over time spell abilities, the two types being Cold DoTs and Chaos DoTs with curse synergy. These builds are very cheap to gear and they are fairly strong out of the gate although the single target isn't insane... being able to drop the skill and then move around is huge against bosses. Occultist isn't a fast ascendancy but Profane Bloom amplifies clear speed greatly and it has a good amount of defenses built into the ascendancy. I expect Occultist to be a strong class for the event even though I expect most Witches to be Necromancers. The Chaos DoT builds can also run every map mod which is big in SSF, it's a nice utility to have.
Saboteur: Traps/Miners tend to be the kings of single target damage and don't have to worry about reflect mods on maps. They can clear fine and safely, they have some in built defenses into the Ascendancy and very cheap to gear. Not much else to say other than Trappers/Miners have been the go to SSF bossers for a while now and I don't see this changing one bit.
Heirophant: Much like trap/miners, Heirophant totem builds can dish out of damage in a safe manner on a budget/cheap build. Heirophant has reasonable speed for a Totem character and defenses. I easily expect Heirophant to be most picked Templar ascendancy for this race.
B+ Tier:
Trickster: Trickster I wrestled with putting in A tier and while it excels in just about every category (defense, utility, speed, budget gear and builds)... I realized that it lacks in high single target. Trickster can definitely map around fast and build up in power with not much investment making it very strong in SSF environment however it's tougher to scale it up in single target damage. Nothing on the level of Traps/Totems/Minions for example. It can still utilize chaos DoT builds like Essence Drain but with not as much damage/curse utility potential as the Occultist. However, for Ignite builds I expect a lot of Tricksters if it Ignite builds are better.
B Tier:
Assassin: Very strong ascendancy now and can definitely do a lot of damage with little investment. Assassin still requires you to go the Crit route which is not as easy to gear for in SSF and the defenses on Assassin aren't as solid as the previous ones (mostly evasion based). However, Asssasin's high damage potential and high speed makes it a powerhouse clearer just as long as you invest heavily into defenses. Expect to see a lot of Orb of Storm/Storm Brand type builds in next league provided they aren't nerfed.
Juggernaut: The premiere tank of the game and a very popular Hardcore option throughout most leagues. Juggernaut is surprisingly fast with its Attack speed node and it's very easy to layer on defenses and then move towards damage. Juggernaut still lacks in damage without a lot of investment as it's mostly an attack based Ascendancy. Spell based Jugg builds like RF have stagnated when it comes to single target and attack builds take more investment to get to damage thresholds (which is why the best SSF characters are dominated by spell characters). But when it comes to defenses it's hard to beat Juggernaut and damage doesn't matter when you are dead.
Chieftain: A very budget friendly Ascendancy with balanced damage and defenses themed around fire and totems. While Heirophant is the better class for Totems, Chieftain can hold its own as well. Many of the nodes on Chieftain are a huge boon to SSF like +100% fire resistance, Endurance charge generation, fire converstion, covered in Ash etc. Chieiftain can easily go spell based and ignite based builds, it just takes a bit to get the speed and damage you need in a race environment. Definitely not a fast Ascendancy.
Gladiator: Gladiator is one of the few classes in the game that is capable of achieving high speeds thanks to Challenger charges along with high defenses with a block focused build. This makes it a very strong option in a Hardcore environment and can definitely hold its own in SSF with minimal investment. Great clear for a melee attack focused class and still the best class for bleeds. Gladiator without much investment still lacks in high damage and needs very good gear to achieve insane levels of block amounts to be comfortable with end game bosses but it's still a contender for Hardcore races.
C Tier:
Champion: A sort of balanced, jack of all trades type class. Champion has balanced damage and defense potential and can stack Impale mechanic to reach ludicrous damage... with investment. Not a particularly fast class either and while it can use autonomous builds like Totems, it's not as good as other classes in this regard. Certainly if you are going a bow build in a Hardcore SSF environment, Champion becomes a solid pick because of Fortify. I still think Champion is a bit niche although when it comes to pure single target damage with investment it's tough to beat a decked out Impale Champion. I am sure someone like DantheCrown will attempt to kill bosses with Champion in this event.
Deadeye: Deadeye is the queen of speed and can get you among the fastest speed/clear in the game with the least investment (and the highest with high investment). However, it is still a bow Ranger class and bow builds are notoriously not defensive in nature... which means despite its strengths Deadeye has been a notoriously unpopular class in SSF Hardcore. Deadeye can still dish out the damage with the bow rework you can still expect a lot of people to try out Deadeye.. I just expect a lot of them to die before they get to the Awakener.
Pathfinder: Pathfinder with flasks can be very defensive oriented however flask builds tend to require a level of investment that isn't really available in SSF. But PF still can provide a lot of utility with stuff like Elemental Immunities and even has option of Poison builds which have high damage potential and can clear any map mod. PF is still very much in the niche side of SSF HC although has potential.
Raider: Raider is surprisingly strong... but for softcore. Raider provides a ton of avoidance now with a good spread of damage and speed with utility like elemental immunity/phasing etc. However, having a ton of avoidance can't protect you in a Hardcore environment for long.. you will eventually get hit. This is just the main issue of the Ranger classes, their primary defenses are through Evasion/Dodge which don't hold up in hardcore when one death can end you. But Raider is the queen of avoidance in the game with ability to achieve 75/75 dodge and 90% avoidance on attacks with not much investment.
Slayer: Like Champion is a mixed bag with some defensive aspects to it (the main one being Overleech, still powerful if you want to go that route), utility (physical immunity) and damage. Slayer also comes with some nice speed and AOE along with being able to scale crit easier than most classes. That said Slayer is almost entirely an attack based class which requires investment to get rolling. You can get good damage going on Slayer and certainly is a solid bosser with Culling Strike but you still need investment to match the other top tier classes. And most of the Slayer builds are still melee which adds another layer of danger into the mix when dealing with bosses you haven't really fought before that much.
D tier:
Elementalist: I might get some flak for this but I think Elementalist is trash right now (pending patch this could change). Elementalist does provide solid damage out of the gate and some AOE... but that's it. Other classes can out DPS it, most classes can move faster and most classes can certainly be more defensive than Elementalist. The best aspect to Elementalist right now are Golem builds which are very difficult to make in SSF environment. While it's cheap to gear Elementalist (making it fine for SSF), it's still a poor class for Hardcore mode.
Inquisitor: While faster and more defensive than Elementalist, Inquisitor is an outdated Ascendancy which is out matched by most other classes especially in the top side of the tree (ie the other spellcasters). This makes Inquisitor an odd pick for most players as it no longer really serves a niche aside from Consecrated Ground builds and hybrid builds. Crit builds are better served going Assassin, non crit builds better on Trickster/Elementalist and even hybrid builds can be done about as well with Necromancers/Tricksters/Heirophant.
Berserker: Bersreker has high attack speed and damage... but virtually no defenses and in fact has noticeable drawbacks to defenses. This makes it a poor hardcore class when you have random degens and you take more damage than normal. Berserker is a very strong softcore class but even in SC it's not as popular as it might suggest. It is also entirely an attack based ascendancy.
Guardian: Guardian is too niche and is mostly used as a support class or mana guardian build. Mana guardian build is not easy to gear for and support class is useless in SSF. This leaves you with specific minion builds which Necromancer does much better. Guardian has defensive utility for sure and can be played in Hardcore with minimal gear... but it's just mediocre in most aspects like speed and damage.
Scion: The true master of none class. Scion without high investment like numerous jewels is a thoroughly mediocre class. Pretty much any top Scion build requires a lot of investment like Ele Hit making it a poor league starter and an even worse SSF class. It is also played as a support class which makes it even worse in SSF as that is useless. There is really not much point in picking Scion for a Hardcore SSF boss killing league.
Let's see how much list changes after the patch notes.
Edit: Actually Guardian should be in C or B tier. If we also include deep Delving into the equation then Guardians can push very deep delves in SSF HC.