Best - Beastie Boys, Hello Nasty at LA Forum in 1998, just tore the place down. I wasn't much of a Beasties fan before that, next day I went out and bought everything they had on CD. Also saw Pearl Jam/Rolling Stones at the Oakland Coliseum in 98 or 99. wasn't a Stones fan so I went to see PJ, the friend I was with was a huge Stones fan so we stayed for about half of the Stones and I was really impressed with them, great show, sounded good, a lot of their older stuff which was great. Can't recall the name of the song, but it is one of their really popular ones that has a chick (super fat black chick at this show) who does the background vocals (very prominent in the song), that just was amazing. Of course, some 60 year old dude in front of us got us high so that may have had something to do with it.
Worst - Johnny Gill, Bell Biv Devoe, Keith Sweat and Monie Love, God was that awful. Guns and Roses in about 1987 at a small place in upstate NY. And GnR. Before Brock loses his shit, I like GnR, but we went to see the opening band and had never heard of GnR at the time. There were literally like 200 people there. During the opening act this guy with crazy frizzy hair comes out into the crowd, sits in the row behind us and pounds a bottle of jack. We start talking to the guy, he gives us some of the jack (which was great, I was like 14 or 15) and goes back to the side of the stage. 20 minutes later he is on stage with a guitar in his hand. 2 weeks later Welcome to the Jungle is all over MTV and they are the biggest band in the world. Like I said, we had no idea who they were which I am sure had much to do with our lack of interest in the show.