Well, I've got about 60 hours logged in on FF Tactics A2 and still going. It's kind of become my go-to game. But I was surprised by how much I've been enjoying MS7. I don't normally go in for those types of games -- not since years ago, anyway. MS7 has inspired me to set up my card with the NeoDS emulator and go back to play the older games in the series. Just finished MS3 this evening, and it kicks ass! I'm getting hooked.
But the game I'll probably be playing the heck out of real soon will be FFIV DS. No doubt about it.