Tor, or Del Rey. Tons of my favorite titles come from one or the other of these publishers. Almost all of my favorite Sci-Fi and fantasy authors have their biggest titles from these guys. Can't go wrong with that kind of brute publishing muscle!*
*Of course you can go wrong, but it's nice to have the biggest and baddest on your side.
Actually, one of my novels has made it out of the slush pile and gauntlet of editors, and is on the managing editor's desk (queue) at Baen Books. It's been there a while. Nothing moves fast in publishing--glaciers move faster.
Baen is known for being innovative and treats its authors very well, and has a very loyal readership.
Tor is known for its variety, number of titles released and strong distribution.
I've met editors (and briefly talked with) from both Baen and Tor. Friendly and truly love their job and books, and interested in author success. That's not to say that other editor/publishers are any different.
And that's not to say I don't appreciate my current publisher who works pretty hard for me/my works and cares about my success too.