Jay Bruce has the highest OPS of any player with more than 20 plate appearances in Major League history.
On another note, if you are interested, here’s an exclusive interview Bruce gave to Redleg Nation more than two years ago.
UPDATE: I bumped this to the top because, of course, I forgot to include the link earlier. Also, I really wanted to highlight this post by Bill. Follow the link there; it’s very touching, and definitely worth a read.