The practice of adapting visual novels into anime has a long and illustrious history, so it’s interesting to see from this ranking just which have accrued most success, if we can equate DVD sales with success (which may be quite reasonable).
Number one should come as no surprise, though it looks as if it will not be in the top slot for much longer…
The numbers are the average number of DVDs sold for each volume (it’s not specified, but these are surely domestic figures):
26,047 Fate/stay night
22,536 魔法少女リリカルなのはStrikerS / Nanoha Strikers
18,170 Kanon (京アニ版 / Kyoani Version)
14,216 真月譚月姫 / Tsukihime
13,360 D.C.～ダ･カーポ～ / D.C. Da Capo
11,251 魔法少女リリカルなのはA’s / Nanoha A’s
10,856 To Heart (VHS+LD+DVD)
9,591 乙女はお姉さまに恋してる / Otome wa Boku ni Koishiteru
8,919 Kanon (東映版 / Touei Version)
8,223 君が望む永遠 / Kimi ga Nozomu Eien
7,189 うたわれるもの / Utawarerumono
6,826 D.C.S.S. ～ダ・カーポ セカンドシーズン～ / Da Capo Second Season
5,981 らいむいろ戦奇譚 / Raimuiro Senkitan
Fate/stay Night occupying the top position is unsurprising, though judging by the success of Clannad After Story, it could soon be at or near the top… It only has to improve on the performance of Clannad by 10% to seize the crown.
Other results too seem unremarkable, though we might wonder at the poor performance of Utawarerumono. Looking for a trend we might conclude that it pays to be unadventurous in adapting a visual novel, since the majority are plain romances?
A look at light novels in this context may also be interesting.