I say if your storage card fits, both. Since you're doing it to see how you feel about them, you might as well. MeeGo might be completely slow, boring, and not exactly usable for anything practical yet, but it has just as much fun-to-try-it factor as NITDroid, in my opinion, so long as you don't expect too much.
NITDroid is probably better for long-term use right now, though, unless you're that excited about MeeGo development.
