Of the 7*, Orage would be the one I want the most. Those "cross" actives are pretty rare and have great application in some farming builds. Three is a bit much.
What crown do you get for your third? The small silver?
No idea on crowns. I just want the sparkly diamond one.
It's nice having the unique active but realistically I've never been in a position to need one. Thouzer works just as well for Amen/Kaede style farm teams and is on a similar cooldown with no secondary effect. I'm thinking it might not be worth Noir anyway. Double 7c + VDP is very strong (see yusuke) but the only team I can think of using her on that I would run is new Dmeta.
So running down the 7*'s I stand by stating Karin is a slightly weaker Ed Elric as a sub. She's strong but the lack of healing on her active makes it a little more dicey to use than Ed and she doesn't provide interesting color coverage. If she was L/G I'd be much more excited. Healer typing means she contributes well to a Narukami teams RCV and can take dragon killers but at Narukami's current damage levels that's not helpful without VDP. I still like her for the record. Her stats are better than Ed and she has the option to be an equip form with skill boost and 2 +ATK which can be critical for button teams.
Elena is interesting. Unlock + ilm + fire skyfall can be vital on lots of fire teams but especially Kenshin/Ilmina variants. Her equip form is another way to get a TPA equip too but I think she's more valuable as a sub with three relevant killers, unbindable, and 2 skill boosts.
Orage is...something? A unique active that synergizes with her leaderskill (1/324/1) and the team HP is always welcome. I wish she had an equip form. I'd use her that way on Zapan all the time. I wouldn't lead or sub her unless I needed to though. With Karin or Elena I have places to put them, or places where they'd fit better than Ilm/Ed. Orage is just kind of there.
Noir is a strong sub with no real home yet. In order to make the most of her you'd want a dark team that can consistently 7c and can make use of a Yusuke like dark/x board change for a VDP kill board. Since her active creates 4 darks it can be used to fix a bicolor without going to far in the other direction too. The problem is this team doesn't really exist outside of anublos. If you're running anublos Noir could be slotted in, but so could any other VDP option like Yusuke, Vney or even Tardis with Super Awakening.
Ralg is another fire row lead with great farming potential. If you have Camael you can burst hilariously high too. The active may have some neat farming applications too. Nothing really special though as a "normal" lead or sub. It'd be funny to see a team of them button stuff though.
Zeta is really good if you can consistently activate. He's even pretty decent if you can consistently 7c. He gets Kyo's double shield (~68% iirc) and his super awakenings are all good. As a lead he's powerful, as a sub he fits on most water teams. His equip is better than Narga's IMO since he clears garbage but also wipes light which might be a problem in some specific circumstances. Either way a strong pull independent of the box.
Raizer is tough for me to read. 3 SB means farming potential, especially since the active floods the board with green. The HP- attack boost would be useful on certain builds too. As a lead 225x for being under 79% is really nuts if you can stay in the butter zone. You'd want to focus on wood for all the HP you can get so cards like Sylvie become important to the team. It's an easier argument to make Raizer into an equip vs Amatsu for the HP especially with Kaede being fragile when her shield is down. Either way a solid pick but more niche applications.