Internal and external arts
I agree that this decision would depend on what you want.
If you want fast self-defence abilities, internal martial arts are probably not best suited. But the question is, do you really need it? How many persons are in the situation that they know they have to defend themselves in unarmed combat in the near future?
I think for most people self defense is more a nice-to-know than a necessity. Fact is, most people don't train any self-defence method, and still survive. To achieve quick self-defence ability, most effective would probably be buying a pepper spray.
Internal martial arts deal with relaxation, body awareness, and mental well-being. I'm a beginner myself, with only 2 years of internal art experience, but I'm thrilled as I get step by step deeper into this world.
I can just recommed to try it as well, as it will also benefit to your heath - bad health is probably bigger danger for most persons than a crime.
The teacher/school ist of course also of very strong importance - I suggest you go to look at different schools and see what you like.
Peace!