Well, the Army are okay as are the RN or wafus. If the Army employed NCOs past age 40 then that would be a good option, so long as you could put up with the REM(E)Fy banter and shocking PT standards
The RN FAA would probably just tip the balance.
But sod that, I'd rather join the Womens Auxillary Balloon Corps than join those two. I joined the RAF, based on what the RAF had achieved, that and it's was 'the family buisness', so I grew up with it.