When you say JB, you are referring to Jetblue, right? That'd be B6

I'm not familiar with the True Blue program, so I can't comment about it. But AA miles are definitely a lot higher value than DL miles. It's almost impossible to get a domestic flight for 25k round on DL. Even 32.5k round will be a challenge. On AA, there should be a lot more MilesAAver availability to get you a domestic 25k round ticket.

If you try Asia for instance, good luck getting 70k round on DL. On AA, getting 70k round is significantly easier. Personally, I feel that of the 4 legacies, only UA lets you off more easily with getting a low tier award.