This isn't excluded to those with songs in the game. Just say who you'd like to see in digital form. 
 
I'd say Badmotorfinger-era Chris Cornell, from Soundgarden:
   

Since there's 2 dead people in the cast, I would love to see Freddie Mercury in the game. Queen is in the game. Granted, with  David Bowie, but if they both make it in the game then it would be even better.

Axl Rose

Chris Cornell, good choice. I would also like to see Ian Anderson, flute intact.

Freddie Mercury fucking owns all. 
 
That said an early Cornell and Les Claypool are stellar suggestions as well (would be nice if we could get some "Rusty Cage" and "Anti-pop" first though), what gives?
 
 
Oh and Animal from the muppets needs to be in GH6, fuck it, just make "GH: The Dr Teeth Band" and get 'em all in there.

Any Rush member, if not all of them.

I agree with Sarcastic Gamer on this issue. They should go the route of NBA Jam, and have characters completely unrelated to rock music, like Wolverine, Alma from F.E.A.R., Martha Stewart, and Barack Obama.

" I agree with Sarcastic Gamer on this issue. They should go the route of NBA Jam, and have characters completely unrelated to rock music, like Wolverine, Alma from F.E.A.R., Martha Stewart, and Barack Obama. "

Dave Grohl. Duh.

For lolz, Varg Vikernes
 
For srs, either Max Cavalera or Steven Wilson.