Finished hard three times.Same. Orisa seems like a must with her shield.
I've also had good games with Lucio.
Someone also showed off a cheeky strat:
When your team has cleared most of the last wave while you defend the cart as it starts up, send your fastest member to the door your supposed to escort the cart to and have them sit there. It bugs EVERY omnic spawn along that route, none of them will spawn.
Stylosa did a 50 lootbox unboxing and the only legendary he got was for Tracer (he got it twice). Everything else was Epic or lower. I feel like they totally nerfed legendary drop rates even tho they deny it.