There are already a lot of good ones mentioned so I'm going to second the top 3 that I think are a must watch from all those. Hopefully with the added vote of confidence, it will make your choice a little easier.
In a Good Way (I would personally translate it to My Freedom Era...college setting in the 90's...a romance and is about troubles of youth in college)
Mars (based off of a manga...rowdy flirtatious outgoing male mc meets extremely introverted and weak female mc in a college setting...a romance)
It Started with a Kiss (season1 high school, season 2 college...based of a manga...also has a Korean version, Playful Kiss if you have watched that before...stupid outgoing girl falls in love with super smart, stoic and cold boy)
I also recommend these 3 that haven't been mentioned.
Gloomy Salad Days (aka Death Girl...episodic stories about a different set of high school kids' issues that may end up in a life or death situation, hence the Death Girl's appearance in their lives. Sorta pessimistic feel to life, heavyish drama)
Mysterious Incredible Terminator (I would translate it to something like Incredible MIT...a little comedy, romance plus mystery....revolves around a club called MIT that solves mysterious cases that happen in their high school.)
The KO series is a cool and fun one to watch if you are into super powers, dimensions, and such. It has comedy, romance and is a bit of a thriller/action. The series/seasons do span a wide time range though, somewhere from 2005 to the latest season that started airing last week I believe, KO One season 5. I think there are around 10 seasons in total within the whole series. I linked the first season in the whole series but if you pick the right season to watch it doesn't matter all that much if you watched the other ones to get what's going on.
In movies, I second Our Times and also recommend Bad Girl and Secret (all high school setting romances).
Hopefully, I have helped you and sold you on at least one of them. (๑>◡<๑)
