Best answer, go train where ever you feel you would enjoy it the most. You want to win fights, and don't mind working hard for it? Sounds like the Muay Thai gym is the one you want.
I'm not sure why its an ethical matter. I mean there are plenty of MMA fighters that train at multiple gyms. It's not like if you pick one the other one is dishonored and looses face or anything.
Isshinryu Karate 2nd degree Black belt.
Neko-Ryu Goshin Jitsu 2nd degree Black belt.
Jujitsu 2nd degree Black Belt.
Isshin-Jujitsu 2nd degree Black belt.