I would definitely get AOD if that is the choice. Depending on the face, it works well and is easy to see and is useful. But for me, more noticeable is the absence of "raise to wake" from my S0 and S3 watches. Both my behavior in having to flick my wrist up, and even more, my watch face flashing on and off when I was not raising it. It didn't really bother me when I had those watches, but now that I notice my watch not doing that, I realize how much better this is. With the S6, the transition from dim to on is very subtle.