BenQ offers one year parts and labor on the W100. In addition they have an overnight replacement program for the first 30 days (they pay the freight). Most manufacturers rely on dealers if there is an initial problem. (As a side note, the more expensive BenQ have 3 year warranties.)
InFocus also offers a one year parts and labor warranty, and no loaner or replacement program. InFocus does, however claim to have longer tech support hours than most other manufacturers.
So the final ranking on warranty - Epson Best, Optoma a fairly close 2nd, BenQ and InFocus; significantly shorter and tied for last.