Check out the full review of the Garmin eTrex 20 and the Handheld GPS Review where we compare the top GPS devices.
Garmin eTrex 10, $110. The main differences are that the eTrex 10 does not have a color display or expandable memory and costs less. The dimensions, weight, and battery life are the same.
The Garmin eTrex 20, $200, is the best value. This is our favorite GPS for backpacking because it's the lightest GPS we've tested (up to 4.3 oz lighter than others) and it has great battery life.