This topic was been raised many times before, and I have before nominated the following examples. For you who have seen them, I apologize, but I think it’s important to counter the sometimes-technically superior examples posited by others (just my opinion ;-) with more, shall we say, musical examples.
- Ry Cooder in John Hiatt’s "Lipstick Sunset".
- George Harrison in The Beatles "Nowhere Man".
- Just about anything by Albert Lee, including his signature solo in "Country Boy".
- Dave Edmunds in "I Hear You Knocking". The most intense example of "tension & release" guitar playing I’ve ever heard.
What makes each of these solos "musical" is that the solo is not separate from the song itself, but is as much a part of the song as is the song’s melody: a musical element.
The same can be said of musical drummers such as Jim Gordon, Jim Keltner, Roger Hawkins, Kenny Buttrey, and Levon Helm. Each player creates parts that act in service to the song itself, not in an attempt to bring attention to one’s own talent (listen to THAT! Aren’t I great? ;-). It can be argued that the distinction between those two playing styles is a matter of musical perception and taste. Well yeah, of course.