Hi Gang,
I love playing jazz on acoustic instruments. I currently play an old Gibson L-4C which is a dream. For the flattop thing I use a Santa Cruz OM with a short scale (24 3/4) that has a spruce top and mahogany sides and back and a Taylor XXX KE (engleman top and Koa sides and back) also with a "short scale" 24.9. I agree with the previous advice about using an OM or 000 model. They seem to be suited for jazz and are very responsive and generally nuanced.
Every player has their favorites of course. And playing a nice steel string is just a gas.
DR
