I play (and occasionally judge) an RPGA game at least every other week, sometimes more often. Most of my play is online; there's a core group of a few dozen of us who enjoy playing together (in various combinations). I also play RPGA at GenCon, and sometimes Winter Fantasy.
For me, RPGA events give me a chance to actually play, as I DM for my two home game groups.
Living Force is my #1 RPGA campaign; I've played every LF module published, and hope my character makes it through to the end of the campaign next year. I also enjoy Living Death (though I don't get to play that one as often as I'd like), and occasionally Living Spycraft.
I played a fair amount of Living City in 2001 and 2002, until they killed the "original" Living City campaign. I played Living Dragonstar pretty regularly until the recent end of that campaign, when Fantasy Flight Games pulled the plug on Dragonstar.
I've played a few Living Greyhawk adventures, but I haven't much enjoyed the combat focus of that campaign, and so I don't really seek out opportunities to play that campaign. (IME, of late, most people who complain about having had a bad RPGA experience played Living Greyhawk, with a pack of munchkins and / or a poor Judge.)
I've actively avoided Legacy of the Green Regent, as they way they handle character advancement and character management don't appeal to me.