If you liked the Your & My Secret manga, the Anime-Planet community thinks you'd like:
Although how they become girls in these two series is not entirely the same, both series deals heavily between the relationship between the main male characters and their close childhood friend. Both series are quality reads, and especially recommended for those into the body swapping gender bender genre.
If body swap themed gender bender is your thing then Your & My Secret and Yamada-kun to 7-nin no Majo are what you are looking for. Somehow those two series are quite similar (although only Your & My Secret has the gender role reversal going on).
P.S. Keep in mind that Your & My Secret get's a bit confusing (and disturbing for some) with who is dating who...