Champions which feel good but lose games?

Anyone else notice this? Assassins feel great to play but most have negative win rates <OMG NOOBS PLAY THEM!> It's at all elos for most assassins like zed, leblanc, and so on. Rarely does an assassin along the lines of akali come along and remain op for long before getting gutted.

There are other champs which are acquired tastes, rammus, amumu, fiddle sticks that have absurd win rates and are really good but don't feel absurd in actual games.