Ive got too many bands and styles i listen to to name a top 5 but ill take one from each style or a group of.
Rock (classic)- Cream, Jimi Hendrix, Led Zeppelin, Aerosmith, Pink FLoyd etc etc.
Metal- Megadeth, Avenged Sevenfold, Slayer etc etc yadayadayda.
Hip-hop (a newly acquired style for my listening)- Immortal technique, NWA, Beastie Boys, Public Enemy, Canibus, EPMD, Zack De la Rocha.
Fusion- Rage Against the Machine (possibly my favourite band

), Nine Inch Nails. (theres more but cant b bothered).
Blues- Clapton, The blusebreakers (Clapton), B.B. King, John Lee Hooker, Chuck Berry etc etc.
Punk and Ska- Pennywise, Shootin Goon, Operation Ivy, Sublime...and the list goes on.
Classical- Beethoven (only coz i have a tape from when i was a kid

)
Sorry if i kinda defeated the point of your 5 favourite bands topic. :unsure:
Edit: OH SHIT, i forgot Van Halen, Steve Vai and Joe Satriani. Also Jools Holland and hi rhythm and blues orchestra.