I suspect you gotta figger out what you want the GPS to do and then pick one
that does that.  Rather requirements-driven selection.  I have used Magellan
and Garmin.  For me the auto routing found on the Garmin V is highly
desirable.  The Garmin II was my first Garmin and I used it frequently until
the GPS III+ was available.  The III+ served me well with it's uploadable
maps and routing.  Garmin provides a basemap, integrates well with Delorme
TOPO, TOPO!, Streets and Trips and of course all the Garmin Software.  Small
in size, with an illuminated screen and the ability to power from 12V, have
an external antenna and connect to a laptop (HP 800CT), I find it ideal for
my navigation purposes.

Garmin.com

cheers,

p