This is a subject i know about... I have had or ridden most of them.

1. Yamaha - my favorite - Good, reliable, reasonable price, solid ATV for just about anything
2. Honda - 2nd fav - good ATV and very reliable, yet nothing flashy, old technology (which keeps them reliable) but no real "cool stuff" factor. Also usually lowest ground clearance and last to adopt technology

3. Can-AM- good ATV, but expensive. also, hard to get parts for these in the past. When something broke, you could be down for weeks waiting for parts to show up. Bomby has to do better here. They are fast but they better be for the price

4. Suzuki - Decent ATV, workhorse reliability very average
5. Arctic Cat - STAY AWAY.. imo - junk. Broke a few of these. they do however look the best, they are sharp but heavy and get poor mileage
6. Polaris - again MY OPINION, but i wouldn't buy one. Broke a few of these too. They are getting better but it used to be that you had 33 zirks to grease and required alot of maintenance to keep healthy. Getting better but again, HEAVY with poor mileage.
7. Kawi - good bikes, reliable but sometimes hard to find service in the midwest if you need it.

all in all, they are pretty good and getting better. i just see the Cat's and Pol's needed to catch up. they keep coming out with bigger and badder ATV's but they just don't last.