I was a sound/lighting tech intern at a nightclub/concert venue when I was in college (not related at all to my major, just did it for fun = aka free alcohol & music), so saw an average of about 2-3 shows per week for 3 years. Got to talk w/ a lot of bands backstage / during monitor mixing too. Most of them are just cool down to earth people. My top 25 in random order would be:
1. Slayer
2. Pantera
3. In Flames (invited 3 of us to their show in ohio the next day, got to drink beers backstage & on the tour bus)
4. Cradle of Filth
5. Dimmu Borgir
6. Danzig
7. Static-X
8. Nine Inch Nails
9. Opeth
10. Rammstein
11. Covenant
12. KMFDM
13. Rob Zombie
14. Dropkick Murphys
15. Tool
16. GWAR
17. Bella Morte
18. Chemlab
19. Carcass
20. Cannibal Corpse
21. Prodigy
22. Black Label Society
23. Ministry
24. Union Underground
(Click me - Mr. Deadman video was filmed at the club where I worked) 25. A Perfect Circle
Edit: added link to the video