This isnt Tekken or Street fighter in real life here hahah. There is no ultimate combos or things of that nature.. To answer quickly, all Martial Arts is very effective or "ultimate". It all depends on the school, Master, and the practitioner :)

What makes you think that you need a combo at all? One good style with a really good teacher, trained consistently and diligently can also be the best fighting style. It's all what you train and with whom.

Definitely a tricked out 1911 colt MK IV series .45acp along with a backup browning hi-power or possibly a glock 19. No doubt!!!!

What works best for you.

What works for me, what I might call the "best combination of styles", may not work well for you, and it will be "the worst" for you.

What's best is simply what works.

And if such a thing existed, why isn't everyone doing it?

Krav maga

What makes you think such a thing exists?

mma