Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
All of em have great and awesome custom avvy's ! (avatar) But i'll pick Sunako's as my favorite ! I have to agree that immortal and Legitmate have awesome Avvys as well.
I really liked how they made such great one themselves !
I like:
1. Abra's--I mean, it's an abra in sunglasses, what's not to like?
2. Bofrocket's-- seriously it's team rocket from the anime I love it
3. Redew- Redew is pretty dang awesome, and so is that avatar. Charizard mega X? Ah, the best.