Kanon

Clannad is basically just a remix of this. Change the season, keep the backstories but scramble 'em up between the girls, etc. Whichever you play/see first has a good shot at hitting, the other will likely fall flat as you've seen this all before. Kanon '06 anime was my intro to Key and while I've got some conflicting feelings about it, I do have more affection for Kanon than Clannad. I'd like to say my appreciation for the winter setting and the Makoto and Shiori routes do it, but it's mostly likely just circumstantial. I imagine it's the reverse scenario for most.

@tphillips i think there's a lot of truth to what you're saying. clannad was my intro to key, but i actually have a hard time deciding which is better. i really love the feel of kanon - the snow, the routes, the music, the overall atmosphere... it's really difficult picking a favourite, but dare i say kanon just edges it against clannad, which is weird because i probably cried more watching clannad.