I'm seeing lots of folks ban Fizz over Zed. Why?

Because Zed is trash tier right now

Both can tower dive and get out.

Tank fizz is back in full force thats why

I feel like Zed has more counterplay overall

When I get killed by a well played zed I think "damn that was a good move nice play" but when I get killed by a fizz it just feels cheap because of how little counter play he really has.

Troll poll + bonus damage from a full indicator. I think Riot did a fantastic job of making the Ult feel more fair to play against (done for if it lands, but not unavoidable), but the bonus damage from whatever basic ability applies it feels too strong right now.