It varies, even within the same instrument.
A revolving list of favorites would probably include Duke Robillard, Oscar Peterson, BB King, Thelonious Monk, Paul Rodgers, Ed Roland, Muddy Waters, Buddy Guy, Diana Krall, Jimmy Page, Sammy Hagar, Billy Sheehan, Brian Setzer, Gene Harris, Miles Davis, Kenny Wayne Shepherd, and if you saw my post on the "most embarassing favorite musician" thread, Neil Diamond, to name a few.