Man did you open up a bag of worms! This is the topic of discussion every time I get to talking with a couple of by buddies. I know people with good and bad stories associated with all brands. I own a yamaha and will buy another because it has been a good bike. Best advise I can give is to go to a repair shop (in your area) and ask the mechanic which models he see's getting repaired the most.
My opinion is that Honda is probably the best bike but is priced high, Yamaha and Polaris are second, Kawasaki and Suzuki are third. All the manufacturers mentioned make fine ATV's and the difference between them is people opinions.