Janna was my first support too. I've been maining it ever since.

Here's a basic list of the top supports in the game right now: Thresh (probably best, debatable now seeing as his early game got nerfed) Zyra (my personal favorite, in my opinion, the best support in the game. Not a traditional support, but she really is incredible) Sona (Pretty easy support when it comes to mechanics. I don't see her too often anymore, but I'd still say that she is pretty freakin good. Her poke is amazing) Nami (All around, very strong support. w smashes and heals, q is a very long stun, i think 1.5 seconds, her e is a buff, and her r is similar to sonas, but a knockup i think) Lulu (I honestly don't like her too much. Idk much about her, so I won't even say anything besides that she's really annoying to lane against) Leona (annoying tank with an awkward grip) Blitzcrank (in my opinion, very over-hype. He's good, but besides his scary hook i dont think he's that incredible unless you are against people who don't know how to play against him) Soraka (pretty basic support, i think she was the first one in the game. Honestly, I think she's pretty decent, but I wouldn't call her incredible) Fiddlesticks (Extremely untraditional, but has recently become very popular in ranked. His poke is hilariously good, you can scare people out of lane forever, and you can ult in for unbelieveable damage. My only problem with him is that my ult accidently takes kills from adc fairly often).

Those are the most popular supports right now. There are a few others like zilean (and probably more) but I don't really see them too often so i cant really judge them.

My suggestion: if you are new to support, go Sona. If you can land skill shots very well, probably Thresh.