AkabeiSoft- They started the trend of moving away from dumb passive MCs for me atleast, most of their titles had pretty unique settings and twists. Wish we get Akatsuki no Goei trilogy translated one day
Yuzusoft- Have to mention them since a lot of their stuff comes here and they are mostly fun little reads, their moege writing just works and they dont try to overcomplicate it.
and third hard to say, Akatsuki Works deserve a shout but i've only got Comyu which is one of the best of its genre i've read from them since Hello Lady seems to be in an infinite state of delay, I wanna say Frontwing because Grisaia is one of my fav ever reads but thats all they've released thats good. Purple Software always does very interesting settings, Hapymaher still ranks in my top 5, Chrono Clock not far behind either and i've heard good things on their other titles as well but no one seems to be picking their games up (Nekonyan picked up one now though, thats exciting maybe we'll get Amatsutsumi later. If they are as good as the other 2 they'r def up here.)
We need more than Nekonyan releasing stuff though lol, wtf are Sekai Mangagamer and JAST doing