I like the Roxas one, it's really good! Everything goes so nicely together in that picture.
But I reallly loove the Sora/Riku one! It's cool how they both have their seperate sides, with their seperate colors, and it's still nicely put together.
The last one is okay, yeah, the text is a bit hard to read, but that's all right. The background's nice, but I have to say, all in all, that Sora/Riku one is really good!!