Which branch should I join?

I would echo someof the others. I was Army enlisted back 40+ years ago and when my daughter began looking to go into the service as a Medical Officer, I strongly encouraged her to go Air Force. Years ago in the tailing days of Viet Nam the Air Force was head and shoulders above the Army in terms of being a much more laid back, relaxed branch that had better education systems and training. Not near the amount of spit and shine and typical military BS.
In more recent years I saw it with my nephew who is a career AF officer. There used to be and may still be a slight edge on ease of promotions in the Army but I think you'd be better off in the AF.