not too long ago, I was asking the same questions. Here is what I found, and why I made the choice for our needs/wants.
I looked at all brands. The vast majority of feedback I got from others that I asked was that while no brand it without flaws, the Garmin brand seems to have the best feedback I found. Ease of use, ease of learning, interface with pc, expandability (sp?), and chips with data are easy to find. Based largley on that information, I decided to stay with a Garmin product. You can also call Garmin direct, and they are helpful with any questions.
ok, so now which one: The GPS 60Csx is a great tool with all the options. At first I wondered if I should spring for the color screen, but it was pointed out to me that just like cell phones, the color screens are actually easier to read, especially in limited light. Made sense to me. That model also had the higher sensitivity antenna. Since we are in the mountains, canyons, draws, trees, etc, and bad weather, I figured that would be worth the $$.
So, did I want to spring for the radio feature? Well, since we already had radios, that was a difficult question. I'm pretty frugal, so I don't buy something to have the 'latest, greatest', or 'new' - I need to see the value, but when the value is there, I'm willing to spend the $. I saw a benefit in the ability to transmit my location to others, or see others' location when they talk to me. (all the Rino's can do this) So, now, which series of rino do you go for? Again, being cheap, my first thought was to buy one with all the bells and whistles, and one really basic model, just for the polling feature. But, the 100 series transmits on a lower wattage than the 500 series. I did talk to some folks that had range problems with the 100 series models (in one case it was just over a ridge). Since then their group has gradually switched over to the 500 series (higher transmit wattatage, and more sensitive antenna) and so far, they have not had range problems. So, then thought about getting on 530Hcx and one 520 to keep the cost down, but I decided that I would rather have 2 devices that had full features and worked exactly the same. The prices I found was about a $60 difference.
So, based on that feedback, I chose to buy a pair of Garmin, Rino 530hcx radios. The "Rino 530 Hcx" has all the features as the "gps map 60Csx" plus the radio capapble of 3 or 5 watts transmission.
I chose to purchase on-line, and saved a lot of money. The best price I found was via E-Bay.
--just my opinion, PM me if you have any Q's
Good luck and I hope this helps.