I've done Shotokan Karate (basically the most common form) for a number of years.
The emphasis on the spiritual aspects would depend on the club in question. One can have a club which emphasises competition, tradition, self defence etc. - so it is a little hard to say what to go with.
A lotof the Karate clubs emphasise the more spiritual side though.
I'd imagine that the non-Eastern type of club are generally less spiritual:
so Brazilian Jiu-Jitsu, American Kenpo, MMA, self defence classes etc. would have a far lower spiritual component.
Martial arts which would have a particularly high spiritual component would be Aikido and Tai Chi for example (if you count Tai Chi as a Martial Art at all).
For self-defence, I would not recommend something like TaeKwonDo - which is generally a ranged fighting style involving lots of kicks. The problem is that most fights start out from in close (talking distance), and in restricted surroundings. For self-defence alone, good quality self defence classes are by far the best, as they do not follow any dogma - just following effective fighting techniques from various martial arts. After that Jiu-Jitsu is very, very effective - combining Aikido, Judo and Karate.
Personally I'd recommend Japanese Jiu Jitsu in particular and after that Karate (Shotokan or Wado-Ryu are good) for the optimum balance of effective self defence training with philosophical training as well.
I don't know enough about Kung Fu to comment on that, I'm afraid.