I'm no expert but I think for realistic self-defense (not just stuff that works with cooperating people) some kind of kickboxing and BJJ can be good. UFC seems like a decent litmus test for valid martial arts imo, however a real fight of course doesn't have rules and in a life or death situation, eye gouging and kicks in the balls are not unthinkable. In my personal opinion based on a bit of training though, physical strength will always have a major effect on how efficient your techniques are. If you don't have a muscle on your body, even perfect technique likely won't help you win a fight against a strong opponent. It's still a great workout though depending on how the training is run. Personally I like trainers who push you and aren't concerned with being super nice and understanding and stuff, it's uncomfortable but makes you fit, heh.