the best thing is if you can spend some time on one.....
there are sooooo many choices any more it's crazy!
polaris is a far cry from what they used to be and if you aren't going to ride HARD or bury it in a mud hole all day long, the polaris has a great ride, power, some cool features, etc.......they really do try to cover all the details......i've always dogged polaris (and still do) but i have really come around on them in the last couple of years.....
any of the major brands make some awesome choices.......expensive but the can am 800 series is off the charts in power.....with a pipe they'll make give up sex with your wife they sound so good....
of course honda still has an awesome reputation i'd say they are bullet proof......the certainly aren't "follow the leader" in cutting edge stuff but they are very solid atvs with proven records of reliablity....
yamaha has something for just about everyone.....they are rock solid too....the grizzly 700 is a very nice quad...i have a couple of buddies with them
kawasaki and suzuki have some nice quads, i just don't know as much about them as i used to.....when we were younger, i knew every model and spec......the field is so vast now, i don't even try to learn them all.....
save a bundle and find a mint condition used one.....
anyway, these are just my opinions, whatever they are worth!