I'd probably list these as "all-time" favourite till now. Although my taste evolves a lot and some bands who are not on the list are very quickly rising up the charts - so Dreamy's list is just as good

(although neither Nine Inch Nails nor Radiohead are anywhere close to the top of any of my lists :-)
1. Red Hot Chili Peppers
2. Duran Duran
3. Level 42
4. ABBA
5. U2
6. Greenday
7. Queen
8. The Beatles
9. Bon Jovi
10. Keane
11. No Doubt
12. The Killers
13. Fleetwood Mac
14. The Kooks
15. Change
16. Ace Of Base
17. Oasis
18. B-52’s
19. Razorlight
20. The Brand New Heavies
Other contenders :-
INXS, The Doors, Black Eyed Peas, Coldplay, Derek & The Dominoes, Jethro Tull, Franz Ferdinand, Talking Heads, The Coral, Traveling Wilburys, The Shins, The Zutons, Nirvana, Spice Girls, The Band, The Clash, The Cranberries