what fighting style is best, kenpo or krav maga?

There is no best if we speak about Martial Arts.

Besides, this is the kind of inquiry that you itself must answer.

Because, there is no other who knows your capability beyond anything else except you, the issue here is not about your own physical ability, things rely upon your willingness and determination to learn, so that you may achieve your main aim, objectives, goal and purposes.

Think so many times and ask yourself if what you like most that can satisfy and make yourself comfortable with, the most efficient way is by visiting some legit dojo, if there are available in your area then go on and observe, ask some important and necessary questions to the assigned instructor related to your concern, maybe through that effort you can decide and push things if what's favor you most pleasingly.

Good luck

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Both will teach you how to be a fighter. I would choose based on philosophy and quality of instruction.

Both of those styles are oriented towards fighting. Shotokan I found more inline with not wanting to fight. E.g. there is no Jiyu Kumite (free sparring) until one is a black belt. In American Kenpo, it starts at white belt. The pro of the Kenpo method is practical experience in confrontation. In Shotokan, you'll have good form before you "throw yourself in the ring" so to speak, and have time to develop the spiritual aspects. Krav Maga, like Muy Thai from what I've seen, seems very fight-oriented.

If you're more upper body, Shotokan has the best straight punch I've seen in any martial art.

I do not like kenpo in general, although there may be some good individual schools.

Krav is sort of like muay thai + jujitsu + counterterrorism tactics.