Um, how about start with the martial art. Study the philosophy. Get good at the former, and learn the latter. They should come together in the end. But to insist one, the other, both, whatever seems to me to be oversimplifying a really complex issue. And it is often done at the expense of one or the other.
So no answers from me. Really I suppose I'm saying the question really doesn't make a whole lot of sense because it tends to imply a necessity of choosing. As if there aren't overlaps, differences, and context sensitive issues to contend with. It ain't so simple... To me at least.
I think the two are somewhat unavoidable...and even inseperable to a degree. Even the least thoughtful/philosophical person I know has "a" philosophy. They just don't think about it much or know how to articulate it in fancy language like people like me tend to like. They still have a "world view" though, and they exercise it all the time.
So to my mind it's not a matter of this or that, but both...and I think it's best to take each one as it comes. On the mat people probably shouldn't generally analyze Locke or St. Thomas Aquinas, but we can chat about this or that while folding hakama, or over beers afterward. Here, online, we can't practice what to do against a punch, but we can consider training methodology and certainly can cover a lot of philosophical ground.