Persona 4 for me thanks to the Endurance Run. It's the only JRPG I've been able to play through since FF9.
I've tried playing P3 but something about the combat grind just makes me incredibly bored -- I was fairly close to not playing through P4 for the same reason. I find both games amazingly stylish though with really fun soundtracks. I own sealed copies of both games, maybe in the future if there's a internet outage for a month or so I'd play through P3.
Edit: I should say I own sealed copies because I prefer emulating most ps2 games on the PC. Just in case that was confusing!