I know this is dumb but i got this from another source not me but if it helps try these (cause i've never seen clannad)
Air
Angel Beats!
ef- a tale of melodies
ef - a tale of memories
true tears
saishu heiki kanojo
hoshi no koe
Kara no kyoukai - hey, near the end it's quite sad
rumbling hearts
Da Capo II S.S
Iriya no sora ufo no natsu
Hanbun no Tsuki Ga Noboru Sora
Kanon
Fate/stay night
Interlude
Tokimeki Memorial -only love-
utawarerumono
No offense, but you shouldn't copy paste a list. Especially since you can't vouch for it, since you've never watched clannad. Which is probably why this list is sooo wrong. Hoshi no koe, KnK and Fate are nowhere NEAR clannad at all. They are worlds apart from what clannad does.
Please have your own opinions, it will help OP out more than you doing a google search. Sure he can do it as well.