My first thought was to make the bar point. Then I saw the 5 point, and couldn't decide which would be better. Then I saw that we could make the 5 and 3 points, leaving some outfield blots. That's the one I like. White has six shots, but a miss leaves white in a bad spot since we can make our bar point pretty easily. I think the aggressive move early in the game is the way to go.
Then I saw what XG thought. Interesting. A balanced, noncommittal play, I guess. It is probably more flexible than what I was seeing. And second best was 0.61 and third best was 0.7 behind the best. My choice was second best.
I'll make 21 and 3. 21 stops any possible white offense in its tracks and allows us to focus on offense. For offense I'll make 3 since it unstacks and we have a bunch of builders already for 5 and 7.
To me it looks a no-brainer: Advanced anchor in opponent´s board and unstack the 6 point
with many builders to make the 4, 5 or bar points. We could well be turning the cube after white´s next 2 moves.
Quick tip -- how much you want to minimize shots depends strongly on the strength of your opponent's inner board. Here White has no board, so your need to minimize shots is minimal.
Additionally, moving up to the 21pt will allow you to be more aggressive in future rolls as the advanced anchor gives you a little insurance in case anything goes bad.