Maple, cherry, and poplar are good, but I also use rosewoods and exotics. I've even made birdhouse ornaments using Lignum vitae. Depending on the style of ornament you make, you might have options to lighten the weight by hollowing.
Branch wood works really well, and I've just found a new admiration for red cedar. Holly is fantastic if you can get some tree trimmings. I've even gotten pieces of people's Christmas trees and made them ornaments from it for the following year.
I do think that the lighter colored ornaments look better in the tree. The darker ornaments tend to get lost.