if your going for one single martial art againts another then combat sambo easily wins because it combines a few martial arts so i guess its cheating. but standing muay thai and on the ground bjj.
muay thai is good, but i mainly went wit wat i know. but mauy thai can be replaced wit good boxing or kickboxing so as long as you got something for your takedowns; wrestling or Judo, something for submissions: BJJ, Sambo or shoot wrestling, and striking; kickboxing, boxing or muay thai you can become a very solid fighter
ninjitsu is very useless and has too many flaws for actual fighting. i beleive most of the art is in the element of surprise which dont expect when the guy is looking dead at you across the ring/cage