Brand me a heretic if you will, but . . . I was never terribly impressed with McQueen as an actor. He did the "cool" thing well on screen, and apparently lived his life on his own terms the way we all wish we could. But his performances, to me, have never been that impressive. I haven't seen everything he ever made; perhaps his Tom Horn, or his character in "The Getaway" with Ali McGraw, would change my mind. Maybe it's that he was often so low-key, as for instance his baseball-pitching POW in "The Great Escape," that he fails to shine for me.
That said, he and my favorite actor, Robert Vaughn, were friends for many years. Vaughn tells some stories about him, I think, in his memoir A Fortunate Life. I'll have to look through it again.
"We deal in lead, friend."
( -- McQueen's gunfighter, Vin Tanner, in "The Magnificent Seven")