If you had a choice between Kunsan Air Base or Camp Carroll, which one would you choose, and why?

In general Air Force bases have better facilities and especially better housing than the Army, so I would recommend Kunsan on that basis alone.

Kunsan. Bigger and it's an airbase. Can't go wrong.

I'd go with Kunsan AB. Facilities are better. It's closer to Seoul and Busan. Other reasons that shouldn't be put on the Internet.