What are the day-to-day life, advancement and general happiness like in 19K, 15U/T or 68C?

Afternoon all,
As the title says I'm coming up on reenlistment and have no intention on staying my current MOS. I've already started working with my retention NCO. I have a few options and just looking for some personal experience from the people here. When I enlisted initially I was an 11B. Got out, and upon coming back in I was reclassed to 74D. I'd like something that is more involved and I'll actually be doing something other than extra duties.

19K interests me because tanks...obviously.

I've always been fascinated with aviation in general and would love to work on helicopters with a chance of being able to fly.

I intend on going to get my BSN when I get out and I've almost completed my AS. I figured 68C would give my a headstart but I'd still need to do a transfer program to RN upon getting out.

Sorry for being long winded, but I'm looking for some information on day to day life, advancement and general happiness in the field of these MOSs. Thank you all.