I've used Garmins. Magellans and some other "expensive" models that we interface with a PC for finding precise locations while on the road ...but for me the Magellan works best. I have an older Map330 wich has been upgraded to the Sporttrack, and Meridian type models.
I'm partial to Magellan, and have used several models over the years. Take a look at the Magellan Sporttrack & Meridian series, figure out what features you'll actually use, some have altimeter-barometer, "electronic" compass and such. For general navigation, these models work great, (for me) the only time I lost signal (briefly), was last year doing Redfield in the winter. On lower rolling hills, I've never lost signal, even in snow covered trees!
I like the topo map feature, but they are not USGS maps.....but pretty close, usually. This requires memory, but for most applications you don't need a whole lot. Another feature you must consider is the screen-display size. On one Garmin unit it was very compared to the Magellan, (most screens are "customizabe"), so you can decide what works best for you, there are large screens (fonts?) so large data sets can be viewed.
It's like buying a computer..if you but the lesser model, you'll wish you bought the better one...and then it's outdated anyways!!!
good luck..