Well to be honest i have been doing martial arts since i was kid. I know that I a going to get a lot of disagreements in what I say. But heres what I have learned.
The best punchers are boxers.
The best stand up seems to be Muay Thai
The best ground art is Brazilian Jiu Jitsu
The best takedowns are wrestlers
the best Self defense system is Jeet Kune Do.
Of course its impossible to do all this. So decide what u want. If you like grappling or u want an art that sjust strictly fighting then u have ur boxing and thai boxing. If u want self defense against street attacks, theres Jeet Kune do. I have done Krav maga and i liked it a lot of people dont. Its the israeli army fighting. SO man decide what u want and what u like and then pick whats best from that category!