Steward, Hull Tech, and Bos'n.
I'm Currently a Suptech going for a OT to Steward I see it as a Navy only Support trade (Flight Steward is a specialty trade).
I add that in thinking of a Job/career post military which one will the market be looking for and which ones will I be able to fulfill.
Hull tech as again it's Navy Only, and alot of duties that will gain lots of experience wood working, plumbing, fire fighting...etc.
Bos'n as I didnt feel like being stuck in the OPS room and they seemed to be the do all when I was on ship.