Dat Sona

I've also been playing a lot of Sona. She's got to be the most complete support champion in the game (with maybe Lulu as the other one). I know that Zyra support is really popular right now but, let's be honest, that's a hyper aggressive support designed to get kills and grow into a carry role. Sona on the other hand lets you play hyper aggressive while still providing buff/sustain. Her level 1 poke is just stupid (if you do it right, you can get AA -> Hymn ->> AA+Power Chord which will do at LEAST 180 damage and probably a little more. That's half the health of a lot of champions.

Her Aria (her W heal) doesn't scale super well with either level or AP. It provides 40 + AP * .25 HP which at level 1-6 is nice but by level 18, you're doing something like 120 + 50 HP which is next to nothing.

But she does a lot more than that. Each of her hymns gives an aura with a fairly significant bonus. You can make last hitting EASY for your ADC by buffing their AD by 8 by level 3. The Aria grants MR/Armor in fairly sizable amounts as well. Typically, I will wait on my first point until I see who the enemy is. If they've gone heavy attack (say, Dorin's and an aggressive support), I'll go ahead and get lvl 1 Q and tell my ADC to watch for a lvl 1 kill. On the other hand, if they've got a sustain champ (Soraka, Taric) then I will often just level my W and harass with auto-attacks (which now have pick-pocket!).

Late game, your ult is the magic. With it, you can do fair damage and stun 3+ people for 1.5 seconds. In a team fight, that's huge. Additionally, I tend to build a Sheen->Lichbane on Sona so that my auto-attacks are doing quite a bit of damage (since I'm permanently bouncing between Q/W and the occasional E. Being able to auto-attack every 2 seconds (coincidentally, your GCD from your abilities) for 100+ ~150 magic damage is pretty nice.