Pharah. That flying rat. The one and only flying hero in Overwatch, is the single most annoying hero of the bunch. Nobody else can fly. Mercy can glide and Winston can jump really far, but no other hero has flight capability like Pharah, which makes her suck. Pharah's missiles are also quite lethal, which means anyone playing her who is even vaguely good at twitch games can do a load of damage, and it's very difficult to counter her.
When I first saw gameplay video of Blizzard's co-op FPS Overwatch, I had thots:
"This is a clone of TF2."
This isn't going to be a long read. The simple answer, and this is a guess, is that HP sees three things.