Most difficult faction?

[Conkercorner]

I wouldn't say Oda, they were my first successful campaign, and while the first few turns as them are an absolute nightmare, and the diplomatic penalty is annoying, things are normally okay once you've got a foothold.

And Tokugawa is basically the same, once Imagawa and Oda are gone.

Uesugi can be ridiculously difficult. Takeda turns into a terrifying beast pretty quickly so you're required to keep good relations with them, but they almost always seem to slip up and get whittled down to 1 or 2 provinces by another clan soon after that, so you find yourself thrown into a horrible new mess against the other clan and its allies as they suddenly become powerful. Also, your starting position is deceptively awful.

Maybe it's just because I'm not very familiar with Total War games in general, but I always end up being ganged up on and squashed as Uesugi, you definitely can't expand as quickly as you can as other clans. Even though playing Uesugi irritates me, I still find the challenge fun.

EDIT: Oh well, I just beat their campaign. That was still the hardest thing I've ever done on a strategy game, though.