For those of us over 60..

If a solo artist rather than a band can be cited, for me it's Iris Dement, then Buddy Miller. While not wishing to sound pejorative, there is a reason band members aren't solo artists ;-) .

Being just 58 I hope I can play in your sandbox....

However with also being English what I grew up with is likely well different to others here.

My defining band and musician would have to be Deep Purple and Ritchie Blackmore. I just dug ( and still do) the whole fantasy escape that music truly is.

While the vast majority of my peers raved over Led Zep and Pink Floyd, I was banging my head to Purple, Sabbath and Hawkwind.

Also Brit and 58.....Bowie. 

This is a very interesting and provocative question OP, and I don't think one band would cover the whole spectrum for me; there would be about ten I guess.
For the present, I'll say Squeeze and Beck. Both appeal to very different parts of me. 

RUSH