I really like GnR, I've probably played that one the most. The music might be influencing my decition.
Ac/dc is also a great game, probably only played it >50 times, but I've enjoyed
I really liked Metallica, I've only played it a handful of times with early code and didn't have time to learn any rules but the shots felt good.
This is a tough choice for me. My money would go to GnR, but I'm not sure how much of that is nostalgia.