I'm also a music freak and have different music that suits different moods (or that appeals to different parts of my personality)...
If I were to try and make a Top 5 list, it would probably be five bands that were very elemental and foundational of my developing love of music:
The Descendents/ALL
Public Enemy
Foo Fighters
Black Flag
Tool
But those selections leave out a lot of the variety of stuff that I probably listen to much more frequently these days, like:
Ryan Adams, F***ed Up, John Coltrane, Arcade Fire, ZZ Top, Purity Ring, Wye Oak, OFF!, High On Fire, Ariel Pink, Best Coast, Bob Dylan, Mission of Burma, Shellac, NOFX, Grizzly Bear, Propagandhi, Saint Vitus, Minutemen, Miles Davis, Merle Haggard, Bad Religion- etc etc etc. I could go on forever!