Bunch of teams have been playing Zen already a lot. His ult is a lot better now, and he's still a beast at killing people, especially with discord being a lot closer to "instant" now.
Ana I guess we'll see, she does counter Zen ult pretty decently, and her sleep counters a bunch of annoying stuff too, plus her ult is stupidly strong without requiring a hard setup like graviton > rocket barrage. Just ult Genji or Soldier and pewpew. Can also just ult Reinhardt and he'll make way, really annoying to stop unless you have Ana yourself or like Roadhog ult to push him away.
I think the main issue atm with competitive is McCree was buffed enough that there's basically no reason to not go with him every game regardless of map or strategy.