I was browsing through one of the JAST catalogues a while back and I was quite amazed to see DOR listed there. It is OLD - in fact, OLD doesn’t even begin to describe it. I have played very few eroges older than DOR and they were all by AliceSoft. Seeing someone still selling it felt very weird.
Best: Brave Soul
Worst: Hitomi & X-Change 3
Not really best and worst, but just my favorites and least favorites.
Best: Yume Miru Kusuri, and Crescendo close behind.
Worst: Snow Drop. I couldn’t follow the story, the way bodies were drawn was extremely awkward, giraffe neck in one scene, and some knees that could only be broken in another. None of the characters were really appealing, it just bored me to the point where I will never touch it again without finishing it.
I liked some things about Snow Drop, but yeah, I had some major problems with it too.
But damn, the song “Ever Stay Snow” used in the opening is just too awesome. It’s been years since I last played the game, and I still listen to it on my iPod.
The best games Jast has releases in my opinion are Brave Soul and Princess Waltz despite it’s linear story. The worst would be Pretty Soilder Wars.
My favorite game JAST has released would either be Brave Soul or Tokimeki Check in! (TCI being the first eroge I ever played, still go back through it every once in a while)
My least favorite game Jast has released is Figures of Happiness. Only redeeming character in the entire game is Shinigami-chan. I don’t remember the hero’s name (Ryo, I think?) , but his incessant need to be an idiot was revolting. Both main heroines (Mio & Minamo?), also revolting. My reasoning will contain spoilers, just in case anyone hasn’t played this yet.
The initial girlfriend breaks up with Ryo? because he went and helped the other putrid heroine find her fucking wallet… are you fucking kidding me? What was her name? Minamo? As a thank you for the favor he does, she steals the main characters life force, leaving him in a vegetative state for god knows how long, because she needs to pluck up the courage to tell some guy she was in love with him. BUT SHE REFUSES TO BUCK UP AND GET ON WITH IT. AHHHH! And forcibly taking your life energy back leads to a bad end AHHHHH… I can’t believe it. She leaves a guy in a coma, causing Ryo and his family and friends ridiculous pain, and refuses to do anything to assuage that pain for the entire game. Basically the entire cast (outisde of Shinigami-Chan/Miss Death) just needed to be tactically nuked into oblivion.
To this day, it’s the ONLY DL’d game I’ve ever deleted entirely from my system.
I think Eien to Natta Rusuban is about to earn that title for me shortly.
Well, if we actually go by titles released by Peter’s group of companies … I think Runaway City is the worst (bona fide Jast USA release, back when Jast USA actually was the US arm of Jast Japan). DOR is pretty bad, but that was a G-C release from back when GC was independent from Peter. (It was one of the initial first batch from them, in fact.)
Favorite Jast USA game … I’m a bit behind, so I haven’t played all the new stuff, but Princess Waltz was pretty good.
Best eroge from Jast I’ve played to completion are: Sagara Family and Crescendo (It does seem weird placing them side by side, doesn’t it? 
)
Worst: Pick me Honey.
In reality I have lots of games in my drives I’ve played to near full completion, which could easily replace both the best and worst positions, but I refuse to rank them, until I’ve gotten every single ending for them.
best- Family Project and I’m Going To Serve You 4
worst- Pick Me Honey (so bad)
Best ; Yume Miru Kusuri
Worst : Pretty Soldier A.D. and Brave Soul
BEST: CRESCENDO (i love it!), KANA (sooo sad!!) and Family Project (very funny)
WORST: VIRGIN ROSTER (the most disgusting protagonist i ever saw) and X-CHANGE (funny rapes?! Stupid!)
Fixed.
My pick for best is Crescendo. I liked all the girls and Miyu is really a cheap shot for me. If you don’t want me to remember you then don’t make me see your route last! I cried manly tears playing it. I do see Crescendo as the best bishoujo game released from the group.
I’ll withhold my pick for worst game because I still enjoyed the worst game I’ve played from them.
-edit-
After some time passed I felt that comparing the two games I almost elaborated on was unfair as their sub genres are so different. Without any explanation, I like Crescendo most as do I think it is the best game released.