 If you liked
Clannad
|
 ...then you might like
Ushinawareta Mirai wo Motomete
|
Both contain friends trying to help others. They each share a similar mixture of slice of life and fantasy. Yui is from 'another world' *ie: alternate timeline/future*, like Ushio in Clannad. Each have relatively sad scenes, though Clannad is much more tragic.
Both anime have very good storylines and are very enjoyable - if you like Clannad, you'll like Ushinawareta Mirai wo Motomete.