Wow, it's hard to say. I had fun in both countries. I was in the Air Force so I got around a lot. Overall, I'd have to lean towards the php. The society is more open than Japan and I think the people are more humble, especially the younger generation people. Being of the same race as you, I can tell you that you won't have a problem finding women. They love black Americans.
Japan on the other hand is also a very nice place. The country is beautiful and the younger generation of people are more open than the older generation. But like I said, it's more expensive to live there.
One thing I learned though is that the police in JP are more stict than the Php. You can't get away with anything there, especially when it comes to safety and driving (very very strict). I got my car towed once.
Also if you don't speak Japanese you will have a hard time. Just about every Filippino you speak to will know English.