what one would you choose and why?
brute force 750 - A very good all around quad, works in the trails and in the woods. Not as powerful as the hotrods like the AC1000 and Renegade 800.
arctic cat 700 mudpro - AC is great off the beaten path. I haven't played with this quad, just it's non specialized brethren. Mud tires and that great AC IRS and the resulting ground clearance are a lot of fun but make trail riding tougher and rock crawling trickier.
can am renegade 800 - A hotrod to be sure, great in the trails too. High cost and the fact that I'm not a big fan of their awd system are reasons I'd back off.
Here's my basic outlook on utes; Polaris is and has always been a true utility quad. Most of their models are best suited to work and chores but still can be fun in a recreational sense. There have also been some new models that are more oriented for such purposes. Prior to the early 2000's they, to be blunt, were riddled with reliability issues of all types from drivetrain to electrics to engines. But since they have come a long way in that field and perform quite well.
Arctic Cat is the Mudder's choice, usually because of the excellent IRS system that allows greater GC without unduly hampering articulation and drive angles. If I needed to haul an elk down a mountain path I'd want an AC to do it with.
Bombardier has always been a bit odd, with the pass-through seats on the traxters (and john deeres) to the first two up seating and so on. BRP uses an AWD system that fits well for trail riders and light off-roading, similar to the Polaris system in practice but geared less towards serious mudding type use. Their chassis and motors have come a long way in recent years, but you pay for it in terms of weight and price.
In fact all of the above companies have a weight premium. Because they are locally produced they do not need to be shipped to US markets and subsequently do not need to meet the approx 600lb standard weight guideline that most Japanese ATV makers tend to abide by. That means the North American produced atvs can be stronger and heavier without a shipping penalty so they tend to be. At least this is the way it has been explained to me by others much more intelligent than I.
Honda makes very reliable utes, and if I was searching for a mid or small bore atv they'd be near the top of my list, but the Rincon frankly was a dissapointment when it was released and the efforts to update it with power steering, EFI and a displacement bump haven't caught it up with the rest of the pack.
Yamaha's grizzly lineup has gotten a lot better this last time around, as the 600 and 660 versions had some not-insignificant problems. The 700 is much more stable and doesn't have the overheating issues the 660 had, and the motor is reliable unlike the 600. IMO they make great all round utility atvs. Never really spectacular in any one area but good enough in all that they are always able to challenge the competition.
Suzuki has good motors and good belt drives, IMO Yamaha's and Suzuki's are the best available in terms of reliability over time even with poor maintenance habits of the user. Suzuki has always made good utility quads back to the robust and capable king quads. The mid-range atvs are good recreational machines and the KingQuad line are very capable from both a recreational and light work standpoint. Another good all-round vehicle.
I've already made it clear I like the Kawasaki v-twin engine. Which is good because frankly they don't have much else to go on. The midsize prairie has always been fairly reliable but not all that great at anything. The small atvs were reliable and cheap but unsophisticated and weren't much fun to ride. The v-twin engine has provided a great baseline for the 650/700/750 atvs based on it. The brute force's IRS isn't anything spectacular but it's setup well for trail riding and feels stable and planted where some other IRS machines get wobbly. There have been problems with the electrics back in the early to mid 2000's, but the design of those components has since been changed and updated a couple of times with successful results. Perhaps a more trail oriented lineup of quads than most other large bore manufacturers but they do a good job with it.
I would suggest taking this question to a forum designated for utility atvs, you'll get a lot more opinions of owners than you will find on this board. I would suggest ATV Connection, Nyroc's ATV site, Highlifter.com, and the like.