I similarly gave 13 a fair go, I completed it even but I don't think at any concievable point I actually enjoyed it, I've had no desire to go back and complete all the marks, the game has been untouched since I beat it.
Honestly had more fun with 12 even though Vaan was a terrible main character, Basch would have been fair superior, much more backstory and a true reason to be fighting against the empire.
That said I've noticed my interest in FF games has waned since Squaresoft became Square-Enix, I have never been able to put a finger on it but the games are just different, they aren't Final Fantasy anymore.