Ditto on what has already been said. When we were shopping, the deciding factors ended up being:
1) How long was the warranty? - Most are 1 year, a very few are 2 year. Gotta figure if the Mfg. stands behind it longer, your odds are better....
2) How good, really, is the dealer? That can be harder, as there are few places to see much in the way of customer reviews. We actually cruised a few local campgrounds and asked those who appeared to be locals about their unit and their dealer.
Troll all the various forums dedicated to the brands you are interested in to see what issues there may/may not be.
Trailer Life magazine has a "ombudsman" column that helps resolve service complaints, which can be an eye opener on how well or poorly some companies respond. Spending time going through back issues should be worthwhile.
Otherwise, it will be one-offs of people loving or bashing a brand, which may not be the best basis, but sometimes is all you have to go on.
Count us among the Jayco lovers going into our 3rd year. The only issues have been very, very minor.