I don't feel like putting free games against others so here is my tentative top 10 free games, I am probably forgetting a tons but whatever
I'll write down a top 10 not-free doujin games later

Free:
DT3 (undefeatable number one?)
Mahou Shoujo + everything from TS
Tobira no Densetsu
rest is in no particular order
詩歌を嗜むRe　
Cyber Rebeat
千変挽歌百不思議
去人たち (I should do 0 soon...)
Erinyes
Various viprpg games like Moshiden, Moshimo Royal, Water is my daughter, etc...
1999Christmas eve or Mimei