Well, it's completely unscientific poll, so you can't really draw any firm conclusions about how the majority of riders, or people who would buy a new quad, feel about the ones listed. Also, my bet is "most" of those who read this forum, are what you might consider "enthusiasts". In other words, take the sport seriously, and demand the most performance from their choice.
On the other hand, its' possible "most" purchasers of new quads are looking at other things. Price, reliability, reputation, different riding conditions, multiple skill level riders who will use the bike,etc. They may not be completely educated on all of the options available to them. And if you realize that the "majority" of quad buyers may be in this boat, you can start to see how the "best" quad for you, may not be perceived as the "best" for the larger population. Of course that's a good thing, cause that leaves more of the "good" ones for those who are in the know..
Oh, If I had to buy a new quad "today", I'd buy a Z400. Why? Well, in my case, I have several different skill level riders who would use it, it has reverse which the wife demands, it's got a decent reliability record, it does have aftermarket support, and most importantly is I believe it's the best "bang for the buck" out there right now. Now, if it were ONLY for me (fat chance!), and money were no object (fatter chance!), I'd get the YFZ450...Can you see how some folks would choose a "lesser" quad?