I see that Sans v6 sprites has preety much likes and I and the team were discussing this and we finnaly decided... that you will choose which sprite to use when playing!
there will be an option menu, obviously, but this will be an option, you can play with various sprites (v1, v4 or v6) and also there can be more sprites for choosing when the full game comes out.

Alright, see ya in next post!