Capital One.
Started with a Quicksilver card, and ended up moving my checking and savings there. I'm happy with it, especially since there are no maintenance fees or anything, and they make everything really convenient to do or work through.
I don't really use the debit card for much, though. Instead I use my AmEx, and pay the balance off each month, so I'm considering moving at least my checking over to AmEx as well. Waiting to see if they drop another offer on me to do it.