Higurashi no Naku Koro ni, Clannad Recommendations
This may sound weird, but both have a guy that somehow changes, affects the other girls' life. Both have drama. In both we can see how a person changes the other's life and life is full of possibilities.
I know they aren't very similiar, but both are really beautiful.
Main girl characters, Rena and Nagisa are very similiar (the same seiyuu, brown hair, and they are so cute!).
And Higurashi and Clannad shows happy and funny moments and sad moments too.
All girls in both series looks happy, but they have some sad memories too.
Eh, sorry for my English.
Ryukushi07 has been inspired by Key's novels for his Higurashi Novel, and we can find similiarities between Clannad and Higurashi (considering Higurashi's Moe, Dramatic and Comic part).
In each show there is a comic character (Keiichi and Suhonara), a female who acts like a boy (Tomoyo/Kyou and Mion), the male character who helps the others (Satoshi and Okazaki), the moe and shy female character who is the principal character's best friend (Rena and Nagisa, they are also dubbed by Nakahara Mai). Both shows have a lot of drama, a lot of moe and a fair amount of comedy.
Sorry for my English...
They both involve alternate realities. Both can be very traumatic at times