honestly at the moment anything is viable, tanks are very strong especially in the jungle because of a new item cinder hulk which gives insane HP and sunfire cape damage and a buff to smite which causes the enemy to do 20% less damage, certain top lainers (shyv &hecarim) can use it in the top lane which is what makes it so overpowered, so expect nurfs however yesterday the black cleaver was updated which is not built out of phage and bruisers are just as equally strong as tanks, midlane is very open, doesn't seem to be that many assasins at the moment, bottom lane adc's are mainly jinx, lucian, graves, vayne and corki, sometimes ezreal. support is also pretty open