I have used magellan, garmin, lowrance, and eagle...by far my favorite was the lowrance but they wouldn;t do us a ton of good in the offroad world cause it was pretty big and quite pricey...
this is one of the ones we use at my work but like I said you will spend right around $2500 for it
(pocket change right
)
personally I really liked my magellan up until it got stolen...I no longer like it
I have heard nothing but good about the e-trex (all models)...never used one though...garmin is a big name and you will get a quality product with anything of thiers...same for the rest really...
as for using them, whatever you learn on is going to be the easiest...since I have used so many different types and models they all seem about the same to me (but really they are different)...for sure get something you can load maps into, its a whole lot easier to determine (enter would be a better word) a route on the computer then it is to try and do it on the GPS (uness you are driving the route)
a very cool option (that I might do sometime soon) is the PDA option...then you could have color topo maps on your GPS and still be able to see it in the sunlight (ever tried to look at a laptop in the sun?) plus if the wife gets bored she can play games...