Yeah, the 13 is definitely the issue here, but I think I would try to do a little work before I moved it. While the 15 is not exactly a "trouble" ball, it is not incredibly easy to get on, and it's not blocking any pockets for my opp, so I might use the 9 (or the 9, then the 11) to try to get a shot on it and get it out of the way early. I would avoid shooting the 12 ball, as it looks like playing the 10 in the side off of it may be a good shot to save for later. Regardless of whether I was able to get on the 15 or not, my very next move would be to try to get that 13 out of there with the main emphasis, as Jude said, on not moving the 2, 8, or 10. The 8 is dead off of the 10 in the side, so any attempt by my opp to break out that cluster will be fraught with peril, especially since he doesn't have any solids at the rack-end of the table that would allow an easy approach from the 10-ball side of that cluster. This rack is very winnable, but trying to go all the way out in one inning is not a good choice unless you can make that 13 cross-corner, as Blackjack suggested.
Good rolls,
Aaron