the first one I tried was Clannad, because when I checked the anime's details on wikipedia after finishing after story, it said that it was just an adaptation, so I decided to fully experience the real thing. It was so great, I read Kanon next. Then I just typed in visual novel recommendations in google and eventually found vndb. That was 2 years ago and Clannad is still on my laptop. Since then I've read all of Key's vns (that are available in english) and a lot of other great pieces.