To the OP - does one or the other have any features or connections that you want that aren't on the other model? That's one of the first things that I would look at.
Power-wise, they look similar. I own the Denon AVR-E400, which is similar to the 2113 (not quite as capable, but similar in power). It could drive my speakers no problem, even at loud volumes. The Denon remote won't control other devices, but the Yamaha's will. I'm not an Audyssey fan because it can't store more than one configuration, but from skimming the manual for the 663, it can't either (I have two seating positions that require different timing adjustments for the speakers - so, I prefer Pioneer's MCACC system).