The STK500 is nice, because it has a lot of headers on it, little clunky to use (a lot of dip sockets I'd prefer a single programmable ZIF myself) But as far as a dev board goes it's still really nice, the main thing you need in addition to it is a good breadboard and the connectors/ribbon cables to breakout the headers on the STK500 to a breadboard. The Dragon is another nice dev board, way better than the STK500, but not for people new. As Russ said, your knowledge/experiance is going to influence what you chose more than what's available.