Just two? Man, that's a tough choice and it depends on what the project realm is.
If looking at building furniture:
Lately I've really been digging Ash. Built my workbench out of it. Going to be building some living room furniture out of it. I've also got the go ahead from my wife to buy some at some point to hoard/set aside for future use, since ash lumber will eventually be hard to find, with the emerald ash borer wreaking havoc. Cherry would probably be my other one - timeless, nice looking wood. Then there's maple and its so many faces and colors.
If looking at the kind of stuff you'd use more for smaller projects:
Desert Ironwood is a favorite of mine. As is Yellow Cedar Burl. And Thuya Burl. And Boxelder Burl (especially flamed). And Spalted Maple (especially with curls or burl). And...
Yeah, forget this whole "only two species of wood" thing!
