Good options either way
The AF is 2000 pilots short, AFRC manning is at 60% retirement eligible, not sure about the Guard. The manning model simply cannot escape the bath tub created years ago with the demand for pilots.
Find a unit, join them, enjoy the new experience. You will be able to find orders to secure the 20 year retirement fairly easy in this environment, and, most likely get promoted in the process. AMC is full of passed over Majors that are now Lt Cols well on their way to an active duty retirement and increasing their seniority at a major airline. Many do it part time and keep both employers happy, it can be done, all depends on your ability to set it up. Remember, if you are at 17 years now, you will most definitely make Lt Col which makes your HYT 28 years. That is 11 years to get three years of orders or 7 if you somehow do not get promoted in the Reserves or Guard. And extensions are being handed out now at even prime units due to the 60% retirement eligible in AFRC mentioned earlier.
Either way you have great options, PM me if you want a more in depth look at current opportunities.
Sorry for the butt hurt of non promotion, it sucks, I saw it many times in active units with folks that have amazing records. However, the manning model says only this many Lt Cols and passover happens. You can determine your next move, it is not dictated by a promotion board.
Good luck and Happy New Year!