Recommendations

Both stories involve a mother who by chance enters an exclusionary elite circle and must confront the superficial and ostracizing rules they set.

They have many things in common:
-Written by the same scriptwriter (Okada Yoshikazu) with Domoto Tsuyoshi as the leading character.
-Both are family dramas too, however Yume no California focuses more on the relationship between friends and their struggle to lead a good life.
-And last but not least Yume no C along with Home Drama are beautiful stories which make us reflect a lot about life.

They're both survival, involving kids/teenagers. Both psychological and suspense genre.

The plot takes place at the same place - a prestigious high school for wealthy.

Same male lead. Both long Taiwanese family drama. Both drama are worth watching.

Both have the protagonist as an adult high school student dealing with issues like bullying.

All In is a classic mafia drama starring Lee Byung Hun, Ji Sung, and Song Hye Kyo. Both have action, intrigue, and romance. All In has a wonderful, surprising, and unpredictable ending. It's overlooked and underrated because it's older.

Both are comedies with a great over the top male leads who are quite devious and hiliarious. If you enjoyed the performance of either one, you'll most likely quite appreciate the other.

Both series have a similar style (plus, the working title for M was so close to TEN that I thought it would be a spinoff at first), both series have a similar atmosphere while TEN is actually about murder cases compared to those cases about missing people.
Also the director Lee Seung-young was involved in the creation of both series, and both are OCN Original series (OCN is a channel with lots of experience when it comes to crime series)

Only based on two eps of FFI I got the picture of two persons trapped in one body which is similar to Who Are You? And one of the sides of one person is mean and the other side is nice.

In both dramas illness does not deter a person from pursuing love.
Both are touching and sweet.

Precious Time is my favorite J romance. Both show the devotion towards an ill person. Precious Time is more realistic and has a surprisingly fullfilling ending. Although the topic seems like a turnoff, it is upbeat and beautiful.

Same drama make by TVB. But so much more better. The main character is a lot more good looking!

Same drama made by TVB. It's the best! Xiao Long Nu in the version is the prettiest and most appropriately casted.

Similar plot, characters, story line, and era. But better looking actors!