I don't have the setup you ask about, but my experience after a bit more than a year in my first Jeep is that the whole enterprise can change you and how you think you will use your Jeep. I just think the likely hood is that you will wish you had 3.73 if you go 3.21; not that you wish you had 3.21 if you go 3.73.
Definitely 3.73 IMO
2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.
There are no winners here; just beguiled participants