The big decider on what you get, is what do you want to spend? Very nice mapping handhelds for 400$, all in, suggest Garmin 76csx, waterproof, floats, put a 4 g card in it if you want, trip computer, backroads figger er outer, Tim's finder, etc. Topo for our entire great nation will fit on that card, btw. Just let that sink in for a minute. You can't be lost ANYWHERE in Canadia with this gizmo!
Very sensitive, too. Looking at its map, it sez which side of the street I'm standing on in front of my house, in the front, or the back yard. It always registers the front porch within 10 ft. 2 AA batteries last for about 18 hours.
If the weather is really cold, I might keep a set of fresh batteries in my pocket on the ice, to keep them warm. Is the problem with your gps unit the screen or the batteries? Try leaving your screen outside overnight with the battery unit inside the house, and hook them up in the morning. This might tell you if the problem is with the screen or the batteries.