I had the misfortune (?) of reading the spoilers and, since I don’t like that kind of ending in my stories, I didn’t really get very far in the series.
I rather enjoyed Mahoraba, and I also recommend just about anything by Komi Naoshi, though I wouldn’t say that his work is especially moving.
I recently discovered ”Eve no Jikan”, which was certainly worth watching (kinda like “I, Robot the novel by way of the various conventions of anime).
Filed in the same part of my brain as Clannad is a series called Kanon, that I also haven’t seen. It may or may not be sufficiently moving.
Your best bet, I would say, would be to poke around Wikipedia, or TvTropes.org, or the Anime News Network’s Encyclopedia.