Clannad is WAAY ahead of every other VN based anime. Nothing even comes close. Key's other anime are well done too but Air was a weak story IMO. I'd also mention Shuffle! as being a good anime adaption, but the Asa route made me say "bleh".
Utawarerumono would be okay if I didn't hate the game's ending already.
I straight marathoned Shuffle! the anime for hours and I regret I actually did that. The anime changed the original so much I don't want to talk about it.
I know there are many animes out there that are based on novels (ex. Haruhi, Spice and Wolf, Toradora, Shakugan no Shana, Zero no Tsukaima, etc.).
So, what do you think is the best anime adaptation of novels?
I say Kara no Kyoukai. KnK anime films are just great (except they messed up 6th one really badly). First, they were very accurate. Second, the animation is very well done, especially the fighting scenes. Third, the soundtrack is just perfect for scenes.
I have no idea what the novels were like, but the Tytania anime series was amazing if you're into Space Opera, it was one of the best sci-fi political thrillers I've ever seen.
Tough choice between Clannad and Higurashi. The first one had a mediocre 1.5 seasons and an amazing 0.5 and the second went exactly where I didn't want it to go after the awesome first season.
So, what do you think is the best anime adaptation of novels?
That's really hard to say. I mean, sure there's Baka-Tsuki, which has some translations of novels, but we also have a lot of anime-based novels with no translations.
Well i suppose to have to agree with Clannad for the best one, 11 eyes has the proper atmosphere tho so we'll see what happens to it.
As for the worst, Tears of Tiara. They added new material in the anime, which wasn't bad but then they had to rush the story and ruin everything that was good about the visual novel. So we end up with that the only good part of anime was a part that wasn't in the visual novel.