In my opinion, FF13 and FFX could not be anywhere much further apart in terms of quality. I even made a thread about it
http://www.neogaf.com/forum/showthread.php?t=989636&highlight=
I would definitely recommend FFX. 13 doesn't represent the turn based nature of the franchise, or even how you run from point A to point B to story sections.
Of course FFX is not perfect. It has some really annoying puzzle points(
HOW THE FUCK WAS I SUPPOSED TO DO THE BEVELLE AND ZANARKAND CLOISTER OF TRIALS ON MY OWN!?)
But if watch a run through on youtube, you'll get passed them eventually.
There's a meaningless sporting event in there too which i never for the life of me ever figured out, so i just mashed buttons the one mandatory time they made you do it(i always loose)
Also, some of the voice performances are pretty cheesy and stilted(although thats somewhat down to having to time the japanese mouth flaps), and its obviously an old game so some things will be slightly janky. But besides that, it holds up well IMO