Hard cold numbers are probably going to be pretty close in terms of resources et al. Personal preference is going to be the #1 answer to this sort of debate. Versatility is just about equal with the exception that gnome uses different wm's.
Options are the same, since you can use both in each other. Everything's equal when it comes to un-biased descriptions. It's the personal preferences that make up the rest of the differences.
Oh, and a search will reveal just about everything you'd ever wanna know about the 2