XII is the only one I've missed so far. After playing X then X-2, I kinda got a bit worried that I might be enjoying the magical girl transformations a bit too much.
But the real reason was that I sold my PStwo on ebay to fund the purchase of my ex360. And tbh, the character designs reminded me of FFIX who I couldn't stand.
FFXIII I'm definitely looking forward to, Versus even more since its more reminiscent of Advent Children.