What's the worst mainline FF game of its time?

I mean probably II, although that didnt release of its time in most of the world. Also launch XIV was so bad they had to scrap and entirely redo it.

Discounting those, I think its XIII. That game launched at a time when Final Fantasy was still THE premier RPG series on consoles. The last game, although not beloved by the fandom, still got great contemporary reviews with a 92 Metascore (an easier feat back then but it was well regarded). And then you had XIII promising to be this huge event that would bring back the cinematic flash, major story focus, and reinvent the series. It landed with a big thud. Just relative to expectations of the time it was such a huge disappointment.