Advent Children > Spirits Within by a large margin, but it is still pure fan-service. I enjoy it for the visuals and the insanely good soundtrack.
I don't even remember what Spirits Within was about anymore. Advent Children had some good fight scenes, and a lot of it was really cheesy, and I enjoyed parts of it, but I don't know if it is worth importing on blu-ray. The movie as a whole was stupid. Maybe the extra content that is being added makes it less bad.
And FFX-2 did have a really good battle system, but not the best in the series or anything. I still wasn't a big fan of either X or X-2 because of the lame characters, story, and settings. Yuna is such a horrible character and I wanted to vomit every time she was in a cutscene. It didn't help that I had this feeling with every character except Jecht, Auron, and Wakka. I'm sure I am forgetting one or two people. Blitzball was also pretty fun! I still don't get the hate for it.