Well, if you like story, FFXII is for you. The main story for FFX-2 might be 10 hours on a slow day, while 12 has a very good, involving story(although it may take a bit to get into)

The main difference is tone, however. 12 is a very serious tone with a little comic relief. In 10-2, I think everything might be comic relief

Dont get me wrong, I liked X-2, but it is really incomparable to the rest of the series. It would be like trying to compare Maplestory with WoW.