Mei is certainly one of the more polarizing characters I've seen. It's like when Mei's on your team (or you are playing Mei) then it's "Mei is bae." The moment Mei's on the other team the response is "HOLY SHIT WHY CAN'T ANYBODY KILL HER BEFORE SHE FREEZES EVERYONE?!"

For me, it doesn't matter what team she's on. Ever since her ult got buffed, people have been playing her left and right without any thought or skill, just because she's "in the meta." I've lost several games to that attitude.