In response to the OP, I don't know what it is with many of the posters in this thread, but they seem very much against the support of the thread queston. Mabey this is because of earlier games that I myself have yet to play, but seriously...
FFX was to me by far a greater game than FF8, FF9 and FF12, and thats making a huge statement, both 8 and 9 and 12 were somewhat underrated but still magnificent games for Square to develope within such short periods of time (excluding 12). FFX was the first ever FF PS2 game, and to me it blew me away as far as graphics and actual voice acting goes.
To fully appreciate the beauty of FFX you need to put yourself back to 2001/2, to when it was released, and for that time like most FF that came beforehand, it was such a triumph, it had aspects of old skool, but also new twists and turns.
The sphere system was new, but easy and additive to the newbie player, the battle system was old fashioned but still had that great sophisticated feeling about it, and the characters and storyline weren't too bad considering the modern day equivalent. I myself even enjoyed the Blitzball games, it was like an extra mini game included.
I won't go on and on, but my main concern here is, to me, at that time (2001/2) considering the earliest game I had played in the series was FF7, FFX was in a new generation, a different league, as far as modern day games went. At that time it really was the grand daddy
And remains my 2nd place game in the series that I've played.