I would say you're really looking at the 1500. The 2500 is 3/4 ton, so it will take a toll on gas.
I had a '99 from June of '99 to August of '06. Never had any major trouble with her. The biggest problem I had was the fuel pump/pressure regulator both had to be replaced fairly early on. But once that was taken care of no issue with it again.
I drove the hell out of my truck. I never had any tranny or drive-line problems. Pretty much was a mash that gas and go type of driver. And fish tail her quite often. If you find one with low miles you shouldn't have anything to worry about. I'll probably always own Chevy trucks. They've been in my family for years and never had issues.
Good luck.
opcorn: