This is a listing of GPS receivers for different purposes; I am trying to provide correct information but specs are often contradictory, even on the Manufacturers' pages. Be sure to do your homework before buying.
minimum requirements
All of the receivers are from well-known manufacturers and have, at minimum, a way to upload/download/transfer between the GPS and PC. USB is substantially faster than serial but for waypoints and routes it's no big deal (a few seconds in my experience). For those that move tracks and detailed maps around alot the speed difference will be substantial. Some appear to only allow transfer by SD card.
terms
waypoint: an X,Y coordinate. A point on the latitude/longitude grid. Frequently imported/exported from the GPSr in a .gpx file.
route: an ordered list of waypoints used for pre-planned navigation. This one, then that one, then the other one. Routes can be uploaded to the GPS and it will lead you from one to the next. A simple form of pre-planned navigation. Compare with "autorouting" below.
track: an ordered list of minimalist waypoints that track where the GPS went; like a ball of string unrolling as you go. You can use this to look back on your experience, or backtrack to where you left your car, dog, children or wallet on the trail. :-) Turn it on and leave it on! If you don't ever need it, fine. If you need it and didn't have it turned on then there are no tracks to leverage.
autorouting: the ability of a GPS+map combination to generate navigation on the fly instead of generating nav routes on the PC and uploading them in advance.. This does not automatically imply voice navigation.
basemap: a permanent and primitive map burned into the GPS' innards at the factory. Unchangeable, but you can effectively hide it if desired. Basemaps generally show cities, highways and major roads, lakes, etc. Crude but Better Than Nothing.
detailed map: additional maps purchased from the GPSr manufacturer to add additional data and/or functionality: topo maps, autorouting road maps, etc. These load over the basemap, obscuring but not erasing it. Multiple maps can be uploaded at once (e.g., topo + city navigator)
learn from the mistakes of others
Here are some mistakes that people make when buying their first GPS:
Buying a GPSr before thinking seriously about their intended and future usage. It is common for a new cacher to think they only want to cache with the GPS, then realize they want to do much more with the new toy. Hike? Connect to laptop? Navigate your auto? Connect to ham radio gear? Use in a canoe? On a bicycle or motorcycle?
Being surprised by the cost of GPS receivers. You can't get an all-singing, all-dancing GPS for $100. Seriously. Technology costs money. There are a few bargains (like the Venture CX) but these toys are not intrinsically cheap.
Buying too much GPS without researching, then being overwhelmed and buyer's remorseful. The high-end GPSr are feature rich and complex.
Buying too little GPS, and being unable to upload enough data and maps due to memory or PC interface limitations.
Being surprised that maps (other than basemaps) generally do not come with the GPSr.
Being surprised that some minimalist GPSr can't accept maps at all.
Being surprised by the cost of detailed maps. Budget $100 for each mapset you want: topo, roadmaps.
Being surprised that map updates are not free. If you want latest-greatest roadmaps you will likely have to buy new ones each year. Older maps are not bad, they just won't show that new road or subdivision. If you are a traveling salesman, or spend time in newly developed areas, or just like being on the bleeding edge you will buy the maps each year. If you are frugal like me and live in an established area you can live on old maps or buying used hand-me-downs.
Being surprised that many map products are "locked", and cannot be transferred between GPS units (Garmin MetroGuide is an important exception).
Being surprised that mapsets are particular to the brand of GPSr you use. If you buy a Lowrance GPSr you will need Lowrance maps. Same with Garmin, etc.
Being surprised that you can't upload maps from generic mapsets like National Geographic Topo or Microsoft Streets & Trips. You can, however, upload waypoints and routes. (Exception: the beautiful and long-delayed Magellan Triton will apparently use NatGeo maps.)
Trying to interface the GPS and PC without basic PC skills. This is not an accusation or insult; I am pointing out that if you already have problems operating your computer, don't expect operating a computer with a GPSr attached to it to be any easier.
Passing up simpler units because they are serial interface. There are usb-to-serial adapters out there for cheap if you pay attention.
This is what most people are looking for, and is the easiest pick. It is hard to go wrong in this category unless you try really hard.
low end:
Garmin "yellow" eTrex (inexpensive, serial. No mapping.)
Garmin "yellow" eTrex H (inexpensive, serial, High-sensitivity MediaTek chip for best reception in urban valleys and tree canopies and improved battery life . No mapping.)
Garmin Geko 201 (inexpensive, small, serial. No mapping.)
Garmin ForeTrex 201 (inexpensive, very small, rechargeable, wristwatch-like, serial cable included. No mapping.)
Magellan eXplorist 300 (basemap, 8MB built-in,serial cable included.)
high end:
Garmin Legend HCX (High-sensitivity MediaTek chip for best reception in urban valleys and tree canopies and improved battery life , color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb cable included, Custom POI.)
Garmin Vista HCX altimiter, compass (High-sensitivity chip for best reception in urban valleys and tree canopies, long battery life, color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb cable included, Custom POI.)
Garmin GPSMap 60CX (High-sensitivity SIRF chip for best reception in urban valleys and tree canopies, color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb cable included, Custom POI.)
Magellan eXplorist 600 (basemap, autorouting, color screen, 8MB built-in, expandable SD card memory for maps like Mapsend Topo, Mapsend DirectRoute, rechargeable, usb.)
Magellan eXplorist XL (basemap, autorouting, large color screen, 30MB built-in, expandable SD card memory for maps like Mapsend, rechargeable, usb.)
This one is tricky. The GPS has to be able to autoroute, and will require $$$ maps. It has to be small enough to carry and be water-resistant at least.
mid range
Garmin Venture CX (autorouting, routable basemap, color screen, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb, Custom POI)
Garmin Legend HCX (High-sensitivity MediaTek chip for best reception in urban valleys and tree canopies and improved battery life , color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb cable included, Custom POI.)
Garmin Vista HCX altimiter, compass (High-sensitivity chip for best reception in urban valleys and tree canopies, long battery life, color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb cable included, Custom POI.)
Since an emergency receiver sits waiting 99% of the time, it needs to be able to run off alkaline batteries (for stable storage) and be small enough that you will be willing to store or carry it.
Waterproof and either floating or connected to your body.
low end
Garmin ForeTrex 101 (inexpensive, very small, AA batts, wristwatch-like, serial. No mapping.)
Garmin ForeTrex 201 (inexpensive, very small, rechargeable, wristwatch-like, serial cable included. No mapping.)
high end
Garmin GPSMap 76CX (Floats! High-sensitivity SIRF chip for best reception in urban valleys and tree canopies, color screen, autorouting, routable basemap, expandable microSD memory for maps like Topo, hackedMetroGuide, or City Navigator, usb, Custom POI.)
low end
Garmin ForeTrex 101 (inexpensive, very small, AA batts, wristwatch-like, serial. No mapping.)
Garmin ForeTrex 201 (inexpensive, very small, rechargeable, wristwatch-like, serial cable included. No mapping.)
high end
ForeRunner 205 (dedicated running functions, high-sensitivity SIRF chip for best reception in urban valleys and tree canopies, very small, rechargeable, wristwatch-like, usb),
ForeRunner 305 (dedicated running functions, high-sensitivity SIRF chip for best reception in urban valleys and tree canopies, very small, rechargeable, wristwatch-like, usb)