Blitzcrank, I support 90% of the time. If I get Blitz in a ranked game with an ADC who knows how to last hit and when to disengage/engage and the rest of the team does "alright" then it's geegee!
If not Blitz, Nami is my second champ to play, Her Q stun is amazing (if landed ofc), W heal and poke can be great for low level aggressiveness while your adc last hits and the ulty Gawd, it can turn a teamfight around so easily.. Ulty into a Q followed by a W bouncing around like mad.
I really enjoy Jungling Nautilus. He has great synergy between his abilities but is not insanely overpowered to where people dont bother honoring when the game is over because you played a brainless champion (Darius, blitz, nasus). I also enjoy Rammus supporting with an aggressive ADC like vayne, graves, or cait.