These are the current tier listings for Persona 4 Arena in the arcades running version 1.02 which will be the console release version.
Tier list discussion informatino gathered together from P4U BBS: http://jbbs.livedoor.jp/game/52991/
The placing of characters in each group do not really have any specific order so take it with a grain of salt regarding characters that are frequently used and those that are not as frequently used.
7/23/2012 -- General pre-console release list
S: Aegis, Mitsuru
A: Teddie/Kuma, Akihiko, Yu, Yosuke, Chie
B: S.Labrys, Labrys, Yukiko, Kanji, Naoto, Elizabeth
8/22/2012 -- Jiyuna's "Opinions from Japan Scene" Tier List, no order
S: Aigis, Yu
A: Chie, Teddie
B: Yosuke, Kanji, Yukiko, Naoto, Labrys, Elizabeth, Akihiko, S. Labrys,
Channels of interest for your Persona 4 Arena viewing pleasure to see these characters in action pre-release
"Defeat is a state of mind. No one is ever defeated until defeat has been accepted as reality. To me, defeat in anything is merely temporary, and its punishment is but an urge for me to greater effort to achieve my goal. Defeat simply tells me that something is wrong in my doing; it is a path leading to success and truth." ~ Bruce Lee