My least favorite entry (excluding MMOs) along with VIII I have played (I started with IV on SNES).
I hated the protagonist and never got invested in the story. The world felt so small and the mini game was a nightmare for me. Overall this was the entry where Final Fantasy ceased being special to me and became another RPG series. Due to its disappointment I actually enjoyed XIII because I didn't expect it to be another IV, V, VI, VII, or IX. I imagine I'll enjoy XV for same reason, but I do not anticipate a return to the golden era of the series.