The first time I played FFVI I didn't find it that good and couldn't understand why people loved it so much. A year or so later, I gave it a second shot and I absolutely loved it from start to finish.

On the XIII Trilogy topic (which I'm currently playing, so no spoilers please) I quite enjoyed FFXIII. Never had any problem with the linearity (FFX was the first FF I played so...) and I liked the characters a lot. Story was confusing at times, but that's my only complaint.
Right now I'm 13-14 hours in XIII-2 and I'm loving it so far.