What is the best GPS for geocaching?

Try the DeLorme PN-40 or PN-60. They come with topo maps and have all the usual caching bells and whistles including paperless caching. I've been using DeLorme for three years, starting with a PN-40 and moving to the PN-60 and have been very happy with them. (I have no association with DeLorme other than being a satisfied user of their products for over ten years starting with their mapping software.)