I would tend towards the arrow version because even in pause mode the full message is still there. With the animation you can pause in a frame and not get the full message the animation wants to show us.
Valid point, and what you're saying is correct.
However, I disagree that this should be the basis on which to choose a graphic. It's my usual reasoning - Lemmings is an animated video game, not a picture puzzle. If absolutely everything has to be clear when the game is paused, why animate anything at all?
NeoLemmix wants secondary animations for a reason: they make things more clear
whilst the game is in motion and being played. I'd say this is a better basis for a decision either way (i.e. whichever version we choose, we need to be happy with the
animated version).
(FWIW, I prefer the Walker sprite version, and will probably go ahead with this for SuperLemmix/my own style sets anyway)