I can’t believe that selecting backerboard could be so hard. I ended up with three finalists: Wonderboard, Durock, and Hardiebacker.

In a survey of Home Depot employees, the inter-webs, and people I know, Durock was the clear loser. Most people were evenly split between Wonderboard and Hardiebacker. In the end, I am going with Hardiebacker, mainly because that’s what my cousin suggested. Also, you can get it with a grid embedded on the surface to make it easier to line up tile, assuming that it’s level.

Wonderboard - notice that it looks like concrete.

Hardiebacker 500 (Actually 420)

Now that I’ve got that out of the way, it was pretty easy to find 1-1/4 inch corrosion resistant screws.  Not sure if the spelling error is intentional or not due to trademark infringement (look carefully, the name is missing an “e”).