>>508716967
Muay Thai, Combat Sambo, Judo and BJJ are the most effective martial arts. All put together would make the most complete 'fighter'. But all of them alone, especially Judo, Muay Thai are the best chances of success. If you have weight parity or more weight on someone, they are not going to be able to defend a random Judo throw and when they're on the ground they're dead. Even if you're smaller, you use leverage.

Muay Thai is probably the second best. Its higher risk but higher reward, if you don't execute well, and you're significantly smaller you still might get fucked up