Subtlety alongside mystery

The good news is there are no blunders in this position (well - unless you chose 7/1* or 8/2 but I’m really hoping no-one does that…).

It’s almost never right to cluster your blots on the points your opponent most wants to make next, so 20/15 is the better running play (24/18 is a mid-sized error).

13/7 strips the midpoint but brings an extra builder into the blitzing zone (but you have a pretty poor structure for blitzing).

So which one is it? It’s a subtle balancing act between different factors. In the end the key things that tip the balance are that White has not yet made any kind of home board, and hasn’t got an anchor in your home board. That means there’s slightly less urgency to run, and slightly more upside to build an attack. The best move is bar/23 13/7. It wins a few more games, wins a few more gammons (sometime blitzes can work even from that structure), and loses slightly fewer gammons. But 20/15 is only a small error.