Which is more difficult. Switching branches as an officer or trying for OTS

I want to join the military (preferably the AF) as an officer, but I’ve been told OTS is incredibly competitive and if you don’t have a STEM major your chances are low. I’ve been told that other branches Officer training programs are “easier” to get into and I have also heard that people can switch branches, but that is difficult as well.

I’m currently in contact with a Marine recruiter and they’re offering a summer program that I can do now or later after I graduate, I just have to qualify first. I want to finish school first so I’m looking at the latter. If I joined the Marines and serve for a couple of years, could I apply for a transfer? (Idk what it’s called).

My chances of joining as an officer as a civilian in the AF are low and I don’t want to wait/spend too long trying too long for OTS if there’s another way.

The AF recruiters I’ve spoken to haven’t been very helpful and are honestly kind of dismissive when I ask questions.

If I’m wrong about any of this please correct me