Let’s hope hero pools and faster balancing will prevent awful metas from taking over the game for 6+ months so we can finally break out of this “loop” the game seems to be in (Blizz releases new gamebreaking hero -> they take 5-6 months at the very least to properly nerf them -> game feels balanced for a while -> repeat).
Also,it would be great if heroes who’ve been stuck in F tier for years got some love and had their major issues fixed
Release valk
Release Brig
I don’t know how anyone can think anything other than these without trolling. Role queue sucks, but GOATs and 100% pickrate Mercy was worse.
Doomfist
Then role q
Automated report system.
That’s not even in top 10 worst things.
The worst of the worst, BY FAR, has to go to Mercy 2.0.
It was the beginning of the downfall of overwatch.
The second worst thing that is far ahead of every other thing as well, but just couldn’t make it to rank 1, Is the addition of brigitte. The game still suffers from the consequences of adding her. Her presence in the balancing alone, changed the game for the worst.
Third place, goes to ironclad bastion. Fortunately though, this one was very quickly patched and handled. Unlike rank 1 and 2 which stayed the same for months.
Honorary mentions are:
D.va 400 armor days.
Roadhog 2.0 after his hook could pull people next to him and even nearly oneshot 400 hp Zarya.
Widow and hanzo buffs, specially since those were done while they heavily nerfed dive as well.
Forcing dive out by buffing everything else instead of nerfing dive.
Junkrat 5 second tire charge days after his major buffs over and over.
Mei being able to freeze multiple characters AND freezing faster and longer buffs.
and last but not least, overbuffing an easy to play hero like reaper that much. Making it average to good for high tiers, while overwhelmingly dominant in low tiers.
There’s more, but these are the ones i can remember immediately.
Oof,so many people saying Brig.
I’m glad we agree that she definitely made things worse for the game
Edit: I really wish Blizz had just nerfed dive back in 2018,rather than release Brig and turn the game on its head.
Your probably not wrong, still don’t like it though. 
222 and it’s not even close…especially in qp (note I didn’t say role q)
I think it pretty much has to go to either:
Mercy 2.0 when it first released lol. Moth Meta was awful xD and I love Mercy
Private profiles.
Group SR limits.
This made playing with 6 friends harder or friends of friends harder.
Nobody wants to play a multiplayer mode that locks out your having fun with a friend because they are too good to play with you or not good enough because of stupid sr
You do know she was F tier with 400 armor until they gave her the extra 100 hp, and the movement while firing speed buff, right?
The roadhog rework which, along with the ana nerfs, eliminated dives only counter play for 18 months.
Adding Ana to the game. The support role was relatively simple and straightforward before her, and since then, every support has to be a DPS support…
Oh and good idea making an ability that negates ALL healing in the game. It’s why she’s either must pick or total garbage…
I’ll take this, please!
… oh, now I’m torn! 
She was also fun, and exactly what the game needed to get over a stale meta.
The utility in her kit was a godsend for me, who was sick of playing Monkey, DVa, and Rein in every match.
So I’m not sure what your point is? Welcoming a new meta to replace an old one is literally what the devs are targeting now. It was only ever a problem because they never patched with any consistent frequency.
Hero Limits, it led to the slide to 2-2-2 and eventually the reverse moba ban pools.
Sigma’s addition.
Completely threw whatever semblance of balance we had out because he was a broken, busted mess.
roleq/222. bad decision.