AW has a nice range of stuff for Ronin forces, lots of good pieces for Bandits or Ikko Ikki models. Plus lots of bits that you cannot get through others, or at least not as large a variety off (palanquins, artillery, etc). Some of their stuff should mix decently with the Perry Minis. A little 'chunkier' in spots, but similar in overall kit/design. They'd also probably match up well with Footsore. Again, slightly inferior, but unless the heights are off they should blend in well once painted.
Assault Group's Sohei are all pretty reasonable as are some of the others. Some I'll grant are 'eh.
Foundry's stuff is a mixed bag, I'll grant you as well. Some of it is a bit funky, but they do have some very nice pieces in there. Again, good stuff for holes in some of the other's kit.
Oh, and I forgot Northstar:
http://www.northstarfigures.com/list.php?man=152&page=1
Then also Old Glory (not great minis, but a different aethetic, that allows for variety. They will be smaller than other MFGs, being closer to 25mm in scale, but if used for a single buntai in Ronin rather than mixing models they work fine).
https://www.oldglory25s.com/index.php?cat_id=257&catname=%27Samuri%20-%20The%20Age%20of%20the%20Shoguns%27