I've had mixed experiences with Garmins, both car and recreational units.
Car units - first one (a Nuvi, forget the model number) was great for many years. It eventually died (screen went white, and I didn't even know what street I was on). The replacement had "improvements" that made the user interface worse, and quit holding a battery charge pretty soon. I've tried friends' TomTom units and I disliked their user interface even more.
Recreational unit -
Had a Gecko, loved it (GPS was still novel then) but it had to be put near the top of my pack to get signal, and the AAA batteries didn't even last a whole ski day.
Eventually replaced it with an etrex Vista HCx - a little larger 4 x 2 x 1 inches, but takes AA batteries which last a lot longer. Has a stronger antenna too. Screen is good in bright light, too.
Garmin annoyances -
1) no screen lock. Every cell phone has one, why not GPS?
2) map management and map software extortion. The hardware is expensive enough. The map management software should be included. No way to swap maps on the unit. (I got the ski area maps from Mountain Dynamics, I'd have to unload them to use a general purpose map, other than the very coarse built-in base map.)
3) track log just records the standard NEMA message data. My unit has a barometer and electronic compass - how about saving their data?
4) track log memory isnt really large enough, though that may be an artifact of the fact that this unit is several years old.
I'm sure the Garmin product lineup has all changed by now, anyway.
I've never looked into Magellan, other than when I got the gecko many years ago. They don't seem to have very good distribution. I'm not going to switch without an opportunity to play with one. Given my lack of experience with the alternative, I'm not voiting.