Some thoughts on Clash. I like this mode for the most part. Perhaps more than any mode in Overwatch it just sort of gets to the point. It's actually recaptured something of the original game for me when it comes to the nature of the battles. It's much more common, in Clash, to die and rejoin the same ongoing fight. Whether this is good in general or not, it's something that sets it apart from the other five modes.
I do think there is a flaw though, bigger with any of the current modes. Essentially it is this: it barely matters how well your team plays for the first two thirds of the match. Imagine your team dominates from the start. You win the fight for C, then D. Winning E is nigh on impossible, so you fall back to D. This repeats with your lead alternating between one and two points until the score gets to 4-3. For all of your team's dominance up to this point, you are one point ahead and fighting over a control point which favours them. If you now lose that one fight you are arguably favoured to lose because your team has to respawn while theirs can start taking strong positions on the central point. It creates a bit of a perverse incentive. If your team is attacking E you don't really want to fight for it. I'm not sure what the meta strategy will be, but it will be something between letting your opponents take the point for free and fighting it in such a way that your team has a resource advantage going into the next fight. Neither of these things is intuitive, and neither will feel good to do or watch.
In other modes dominance pays dividends. In Push, Hybrid and Escort every metre the cart moves, and every second it doesn't counts at the end. In Control and Flashpoint every second your team has the point and theirs doesn't counts. By contrast, in Clash, you gain points for clinging onto the game. The reward for successfully defending E is that you haven't lost, it shouldn't be a point.
I think this is quite easy to solve: change the scoring system so you don't gain a point when you take a control point on your side of the map, i.e. if you are attacking towards E, you only get points by taking C, D, and E. This maintains the property that the winning team is winning the tug of war, but unlike the current system it rewards dominance.
Then there's the endpoints. Clearly on a basic level it feels like it's far too hard to take them... but the balance here is difficult. We can see what it feels like when taking it is nearly impossible, if it were too easy to take games would regularly end in two minutes while the struggling team tried to figure out their response. I think in some way they're going to have to make it easier to take the end points as the game progresses, to get the best of both worlds where it's hard to win 3-0 but more viable to win 4-1, or 5-2.