To Heart

Both shows are epsiodic in nature, and both have a nice relaxed feel to them. Oh, and both shows have a female lead called Akari :) 

Both series deal with the strong bond between childhood friends who ultimately fall in love. Also, both are episodic in nature, and both are very calm, relaxing animes (there's very little in the way of angst or drama in either of these). If you enjoyed one then you should enjoy the other. 

-Calm anime -Both protas are very friendly and laid back and they care about their friends -There is a robot in his group of friends and the protagonist's childhood friend 

both are very cute and a good romace/comedy. 

Both happen to be slice of life anime with a male protagonist, who interacts with females, each having distinct character traits. Take Golden Boy, remove the ecchi, make the male protagonist a more serious person, capable of romance and finally domesticate it into a high school setting - voila! You have the skeletal plot, theme structure for To Heart. If you liked Golden Boy but felt the need for something more serious and possibly genuine direction, go for To Heart. On the other hand, if you liked To Heart and felt that you need something similar that is not constrained by a high school setting and coming-of-age romance, something more "otona", then check out Golden Boy!  read more 

While To Heart and KimiKiss differ in their plot structures, both are primarily interaction driven and could be considered to be different takes on portraying the possibilities that the relationship between childhood friends hold. Note that both are non-harem romance anime set in a school setting, exploring about 1 year in the central characters' highschool lives. To Heart is much more subtle than KimiKiss but chooses to focus on being a slice of life show while KimiKiss uses plot drama and gentle slice of life nods, to tell a romance.  

Neither To Heart nor Sketchbook are in any rush to tell a story, or to create complex characters. What they excel in is escapism. To Heart is about the wonder of meeting new potential love interests at anime high school; Sketchbook is about a sensitive person cherishing the simple things in life. Both are relaxing shows with innocent loveable moe girls. Also, both have a cheerful American character who speaks comically bad Japanese, and a quiet and gentle girl with long, black hair. 

If you like this show about pretty much nothing, than you might like this other show about pretty much nothing. 

To Heart is the anime (and dating sim), that the main characters are fans of. If you're a fan of Comic Party then To Heart is a must watch - if only to make the jokes clearer. 

Both are "Slice of Life" shows, that are slow paced, have very little plot, a bit of drama (and very small hints at romance), both involve a group of friends and their relationship with the lead character (Piano Main Character: Miu Nomura ||| To Heart Main Character: Hiroyuki Fujita). Both shows lack action, and have a very limited use of humur. Both shows have a bunch of interesting characters (that don't do anything interesting the entire series), and both shows can be considered "coming of age stories". Also both To Heart and Piano are realistic (well To Heart has some non-realsitic parts). However both shows are different takes on this genre. To Heart follows a male lead, while Piano follows the female lead. If you like To Heart, watch Piano! If you like Piano watch To Heart! read more 

Schoolyard slice-of-life's with romance and a (sometimes alarmingly) upbeat heroine. 

It's not very mystical or supernatural about this series, but it's very similar when it comes to the characters. The main guy in To heart are just as helpful and friendly as the main guy in Clannad. He helps out a lot of girls that he meets. The girls's personalities in To Hart are very similar to the ones in Clannad  

Both series contain the romance theme hence may appealing to the shoujo demographic. There is humor, interesting characters, and has a similar style that gives off a nostalgic feeling of the old school atmosphere. Both series also takes place at a school setting with other characters involved with the typical gags and drama.