If you liked
Fushigi Yuugi
|
...then you might like
Harukanaru Toki no Naka de
|
Very similar stories featuring the four gods. Normal girl is transported into "another world" where she is told that she's a magical priestess who has to work with her many bishie guardians to summon a god. The characters are different enough that it doesn't seem like you're reading the same exact story, but still fill very similar roles in the plot. Fushigi Yugi is a bit more romance-y, while Haruka is more harem-y, but there's quite a bit of overlap in how the romantic subplots develop.
If you liked
Ouran Koukou Host Club
|
...then you might like
Barajou no Kiss
|
Reverse harems featuring heroines that often find their boys more tiresome than anything. Very different stories and art, but similar plot development and reference-based humor. Neither takes itself very seriously. Ouran is a bit more self-aware and has some more meta humor, but I think if you laughed at one you'll probably laugh at the other as well. Also, Tamaki and Tenjoh are very similar.