i have to agree and disagree with some of the posts. I think that Yamaha and honda are the 2 best with suzuki as a close 3rd.
If you stick with any of these 3 you will be fine. However, it's important to note a few things. What do you want in an ATV.. just reliability? if so then all 3 again are fine. however, do you care about ground clearance, belt vs drive transmission, 4x4 with locking diff? this all makes a big difference.
let me explain. i just bought a 2009 Grizzly 550 yamaha. Best ATV i could find. I have had many yamaha's and all are rock solid. My entire family drives Honda so i have been around both for a long long time. The reason i went with the grizzly is;
1. true 4x4 with locking diff... THE HONDA does NOT offer this. I see this feature as a must
2. better ground clearance. This is so important when crawling thru the woods. HONDA has the lowest clearence.
3. belt vs drive - Honda has a automotive type trans.. you may say thats great but the maintenance of this or repair is so expensive its not worth it. The others all use belt. $60 buys you a new belt and your done. Yamaha also has the most efficient belt drive in the industry.
4. Honda's are small. the grizzly 550 is full size.
Now, honda's are great machines and they are reliable. But they don't change. they don't have any of the new technology the others have. they are resting on their laurels. At some point they need to put some of the things people want on their ATV's. Again, locking differential should be STANDARD on an ATV. Honda doesn't offer it.