Depends on what you want the GPS to do. If you are looking for something that can simply tell you where you are and the direction to waypoints and such, than most any $100 or so GPS can do that. I had a Magellan initially and went to a Garmin 12 since I needed something that could connect to a laptop. The Magellan was ok, it had pretty good run time for two batteries, but it was somewhat slow to initialize compared to the Garmin. The Garmin takes twice the batteries and lasts about half as long due to the different types of displays. I think 8 hours or so depending on backlight use, contrast, etc, for the Garmin on 4 AA batteries is about average for me. I usually have it connected to a vehicle power source though.
Glenn