For years I have used a Garmin etrex, the base model of the range. It's ok, I use it mostly for geocaching rather than much else. It has it's flaws, the battery life is poor, and if you drop it it turns off, if there is a lot of vibration, it turns off, it turns off randomly when walking, without telling me and then I lose some of my track and so on...
These days I tend to mostly use my android smart phone, and an app called view ranger. This has a number of useful features. The main ones I rely on are:
- Location with a map - the default is open street map, but you can pay and load OS 1:25k maps.
- Tracking - Keeps a log of my route so I can draw pretty maps later (see below)
- Buddy beacon - At a set interval (every 5mins to every few hours) it sends out my location, meaning that if something happens the local search and rescue can come find me easily. (Mainly as a friend in said SAR group has access to my beacon).
- Loggint positions - So I can record my campsite location, useful trees (most of my points are called "Hazel tree" "hazel tree 2" "sloes" "more sloes" "damsons")
The downside of all this: battery life. This is largely dependant on your handsets battery life, but can be very poor.
Hope this helps.
J