Er…How do I describe this?
Maybe the company gives off a certain essence?
Or
The feeling while reading it perhaps gives off a “vibe”?
Example:
The Minori logo
Seeing that on my Minori games makes me feel classy!
For me, propeller. I wouldn’t say they’re my favourite eroge company or anything but the name just screams ‘good design’ to me. Their upcoming title looks nice as well; there’s no propeller game I haven’t loved, although that might be because I haven’t played their first title w
Other than that, maybe keroq/makura? All their games are unique- none can be accused of simply playing to the standard eroge stereotypes, and while they vary in quality, they’re all pretty special and I haven’t hated any of them (although I’ve come close with TV no Kieta hi)
EDIT: If doujin circles are permitted, my answer changes. Plastic Label. They’re indescribable.
Yeah,doujin circles are aloud : ).
Edit: are you trolling me?
For me it’s Innocent Grey. Their games are simply beatiful - fantastic art, wonderful soundtrack, great plot and characters and even good ero. I loved ever single one of them, and looking forward to Kara no Shoujo 2 
About Plastic Label? why on earth would you think that? =P Their games are really quite special; they combine the trainwreckery of an 0verflow game with interesting characters and an enjoyable story. Well, enjoyable depending on the sort of things you enjoy, of course. ??? is their best game, but ??? is also worth playing. (if you’re going to play both, play ??? first).
Trainwreckery as in bad?[size=50]durrr[/size]
http://www.youtube.com/watch?v=_5E7zgFJ7DQ
I’m not seeing any sign of quality [size=50]Unless thats what they were going for…?[/size]
beginning reminds me of clannad.
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The thing constant about Plastic Label games is that they’re never going to turn out like you’d expect.
Literally depends on the year for me. 2001 to 2004 I would have proclaimed Touchy. 2004 to 2007 I would have proclaimed Black Cyc. During and after 2008 I stopped being 100% devoted to a particular company that I worship above all others, and now cherry pick from the sea. Unfortunately I’m now of the mind that the “Dark Eroge Golden Age” ended around 2008. I mean studios that didn’t specialize in dark eroge, were making good dark eroge back then (for example Draculius by meromero cute). Everything is either a rehash of the old glories, mindless tenacle orgyfest, or overhyped disappointment that falls short of rekindling the candle. There are occassional bright spots that give me hope though… 2009 had Mugen Kairou 2.
But no one studio has my undying trust at the moment.
That reminds me … isn’t Draculius that vampire game where the protagonist is the new leader of vampires and yet still goes to school, and it turns out one of his classmates is a vampire hunter? I seem to recall you had reviewed it on your site (and it sounded interesting) but then the review was lost when your site got hacked.
Aye. I managed to put that review back together though: Draculius. It also has someone trying to run a Xanatos Gambit, which makes the plot interesting. Rian and Rika really steal the show, though Elshlant gives 'em a run for their money. 
Great eroge IMHO… not alone in that either. It’s only major failing, was not having a larger budget, so things are cut short here and there… though that’s no fault on the developers. If you can play it too, the PS remake had a longer plot and extra character that made everything seem more “complete” in the end (it dropped the sex, of course).
Whoa, it’s written by Fujisaki Ryuuta? That alone makes it worth grabbing for the DLsite price gets