I'm guessing that since you already have an AD2 and you love it then you probably also have the throttle control skillz that go along with running 2wd trucks. I would go with the Losi. I have driven mostly onroad and years of 2wd offroad stuff and the 8ight just felt natural too me. Like running 2wd mod but with more forward bite.
Can't wait to try out the O'donnell though! (shameless plug)