I just bought the Garmin eTrex 30 and love it. I found it on eBay
for $249 new. $50 savings over retail.
I went with GPS satellite because my phone does not get reception where I trail ride.
It tracks my speed, distance, time, elevation and my route to name a few features. I can add location markers (waypoints) during the ride.
The waypoints allow me to repeat the trail ride on another date and will assist if we are lost. I can switch views and discern my general location based on the stored waypoints. If you are close to civilization you can find nearby roads, etc.
Pretty much all GPS units do the same thing. The technology is pretty standard between manufacturers and brands. Your real decision is based on the price, display, size, battery life, memory capacity.