If I had to pick one, I'd say AK. But, here's an idea, and I don't think any other team has done this:
You don't retire the jerseys, you retire the 2006-07 team that made the WCF.
There are a lot of well liked and notable players on those teams, including the team with AK and Harpring that almost made the playoffs when Stockton and Malone retired. That group had us back to the WCF in what, 4 or 5 years? We had multiple all-stars (Boozer, Dwill, AK) and AK was All Defense three times. Boozer was the first big free agent acquisition in team history, and we may have been set back years if that hadn't happen. Keep in mind, a lot of those players did charity work for the community, too.
So, you take a night, bring in AK, Memo, Deron, Boozer, Harpring, even Millsap, anyone else that made a contribution, and you retire them as a team. (anyone except Fisher.) You put up a banner of the WCF team with all of their names on it. Other players can still wear 8, 13, even 47, but those players are still honored. Best of both worlds.