no.1 Clannad and clannad after story clannad isn't so heavy u can still handle ur tiers and so ... but clannad after story is really really heavy on drama ... i couldn handle my tiers but if u don't watch clannad then u ain't going to know what the he is going on in clannad after story ...
next one hmm idk maybe it would be itadzura na kiss ... or aishidzure na baby ...
i loved them all haven't watched anime in quite some time now so i somewhat forgot the best ones but i still remember plot of the ones i really liked and thoes 4 which i mentioned were one of the best ...
Clannad
Clannad after story
itazura na kiss
Aishiteruze baby (i love you baby) i found it in english title
La Corda D'Oro - musical anime has romance and drama
Myself; Yourself - has kinda heavy drama
Suzuka - Has nice Drama
True Tears - Awesome anime overal drama , romance bot much comedy
really good drama i would say i cryed
Air - Has nice dramas as i remember