Actually from my posts you still don't know which brand I prefer do you?
I've been slow in wading in on this one, because of potential biased viewpoint. But, I went through a similar process last year, looking first at golf cart deriviatives (including 4wd), pure utilities like Gators and Kubotas, and even Kei trucks -- then went toward a combination of work with some serious fun mixed in...
IMO, if you want to combine work and have fun on the trails with it, there's really only four good choices out there: Kawasaki Teryx, Yamaha Rhino, Arctic Cat Prowler, or Polaris Ranger.
The Rhino is the smallest and the lightest of the group, at about 1050 lbs, with a 400 lb bed payload and 1200 lb towing capacity. Is that enough for your needs? It comes in 450 and 700fi models, including a 700 Sport model with high-performance reservoir shocks, etc. The Rhino 450 is the least expensive of this group.
Next size up is Kawasaki Teryx. Wider, about 200 lbs heavier, but considerably more power. Roughly the same payload and towing capacilty as the Rhino. Newest design of the three major players, and has just gone through its first major "refinement" in a new model. (I don't consider the simple addition of fuel injection to the earlier design to be a true "new model." Earlier ones were notorious for belt problems, when put to hard use -- not sure on this new 2010 model.) Price is comparable to the Rhino 700 -- which it was targeted to directly compete with.
Comparable in size, weight and capability to the Teryx, though much faster in the 1000cc model, is the Arctic Cat Prowler. The 1000cc is the "hot-rod" of this market. Available in 3 engine sizes (550, 700 and 1000cc), it also sells the fewest (last I knew), and is likely the least refined/least proven of the group. It too, was designed to compete with the niche-defining Rhino. However, given competitive pricing and good local dealer support, it would be worth a looksee.
Bigger still, more powerful than everything but the 1000CC Arctic Cat, and likely most expensive is the Ranger 800, with the largest payload and towing capacity. A proven desigh that has evolved and been refined over the years -- and some of the reliability issues have been addressed. It was initially designed to compete with JD Gators, with more serious off-road capability. It has the largest bed, and can haul 1000 lbs in the bed -- if you don't mind bottoming out the rear shocks and staring up at the sky while driving. (note that both the Rhino and Teryx would haul FAR more than their rated payload, probably at least twice that, if they were put in a similar "overload" condition).
There is a brand new Ranger 400 midsize that is smaller and compares in size more with the Rhino and Teryx. There's not a lot of info and feedback on it, since it is a new 2010 model, and there's not many in showrooms (at least around here). It's more expensive than than the Rhino 450, yet less expensive than the rest. The new-for-2010 midsize Ranger 400 wasn't available when I was looking, nor the redesigned 2010 Teryx.
I recommend that you start with test driving these four machines -- determine what's different between them and which of those differences best meet your needs. Then, look at the different models that that brand and specific model allows (only the Teryx comes in a "one-size-fits-all" model line.) I decided the Rhino 450 met my needs well enough and gave the most "bang for the buck". If I need to haul 1000 pounds, I have a tractor, a 4WD pickup, and three different trailers to choose from. Since I ride in the mountains/hills, and will retire to the foothills of the Smokies, the engine braking (unique to the Rhino) was a major selling point for me. The rock-solid reputation for reliability (second only perhaps to Honda machines) was also a big factor.
Note that I left the Honda Big Red out of this group simply because it is as big as a small pickup and really too large for trail riding. It's more in competition with the Kubota RTV 900/1100 machines, not the ones I've discussedl.
How you'll use it determines which is best for you... this is much like buying a pickup. There's a world of difference between a 4-cylinder Ford Ranger and 3500 Ram MegaCab with a Cummins -- and lots of choices in between!