it's hard to pick cos i've been to a lot of shows and i've had some pretty good ones for different reasons.
best would be my first ever GA show. first dose of the intimate, indie experience w/ a local band, sleater-kinney. i was just loving the crowd and the band and the people . even tho i basically hadn't heard of them til that night. but it introduced me to everything. and there was some cute lesbians making out and slowdancing next to me
when i finally got to see smashing pumpkins live, my most favorite band for YEARS that i've obsessed about (20+ albums including bootlegs..) ....that was pretty intense..
flogging molly was a definately feel-good show and i loved being in the pit. it was so happy. haha.
and my most recent best was metallica. i had to sift thru some sucky bands before the real thing came on :P but it was worth it. and the pyrotechnics were great. and the pit was scary but i experienced like, 10 minutes of it. i just liked experiencing it with my ex. sigh. it was really awesome. bcos we were both really into it. headbanging and everything :-D