Originally Posted by LogicalTautology
Rough order imo: Blitz, Ali, Taric, Leona, Janna, Sona, Lulu, Nami, Zyra.
In terms of consistency across all players, I've found that Taric, Sona and Nunu (in no particular order) are the three supports that people tend to do best with.
I've played with one really good janna, and I never see nami or zyra. Can't really comment on lulu - I barely even know what her skills do, lol.
That said, in terms of which supports I personally like the most, it depends on my ADC. In general:
Nunu, Leona, Taric, Blitz (that's right, he's not my first), Sona.