In my opinion, here's who should.
- Barry Allen
He's "run his course", you could say. This would be a perfect way to re-introduce Wally West and make him the new Flash as in the comics. That would be a great way to change the status quo.
He's a good character, but this would be an opportunity for Superman to sacrifice himself in a way that means something. Also, Supergirl could easily pick up the slack and fly out of her cousin's shadow.
He's kind of annoying at this point. Also, Ryan Choi could easily be introduced as a replacement, since The Flash's first Season 5 episode confirmed he's out there.
I don't think Green Arrow should die, but his show should end. Supergirl shouldn't die either.
Who do you think should die?