http://www.gpspassion.com/forumsen/default.asp?group=2
an international forum.
Home page has reviews and articles.
Do not just look at the name brands, look at the chipsets they use as well. SiRFstarIII is the most sensitive of the bunch.
Garmin makes good GPS, so does TomTom. Figure out what features you want and find the model that most closely fits that criteria. You, probably, will not not know what you want until you read up on what is out there.
For example some of the lower-end GPS will lead to an address, but won't tell you what side of the street the house is one, some do. Is it important to you? Different manufacturers have different prices for the map updates. If you use GPS pretty heavily, you'll need to update maps at least every two or three years. Add that to the final cost. International maps, directions in other languages, is it important? How easy is it to program a route with multiple stops? How fast is TTIF (Time To Initial Fix) after a boot?
Does it work at walking speeds (with some you need to move at least 10 mph to get a location fix)? I like to walk around with my TT1 when I visit a different city. Makes finding restaurants and places to see much easier.
Does it have a built-in battery? How long does it last?
How well designed is the mounting system? Can you connect an external antennae to receive traffic blockage info or a stronger GPS antennae?
Can you load topo maps, if you plan on taking it hiking? How water resistant is it?
How easy/intuitive is menu navigation? Can you use thumbs or do you have to use a stylus? Can you pair it with your bluetooth phone?