Azusa is my favorite, but I amor all of the characters! I think it's not fair for the others that Mio gets all the attention since EVERYBODY loves her, but of course I still like her too.
For me I like mostly every character really but my number one has changed between Yui-chan,Ritsu-chan and Mio-chan exclusively and my topo, início three has changed a lot between those three to be honest but right now Mio has to be my number one favorite!