I love both! depends on my mood when I watch it.
I started out with jdramas. I love how they portray the feelings so well and the stories are almost never cliché and so unique. the lines are very well thought out and you can really learn a lot about Japanese culture from most bc it's so engrained. on the whole, jdramas tend to be better written...especially crime. but the production quality is a lot lower and pretty homely. I prefer jmovies most bc they have amazing stories along with high quality production.
I usually watch kdramas when im in the mood for more glossier stories and a pretty cast. I love how Korean culture is evolving and you can see it in the kdramas. the trends are shifting and newer kdramas have better written characters with lots of women centric plots and cover a lot of issues.
jdramas have always been doing that but jdramas tend to be a lil heavy to watch while kdramas are comparatively lighter. honestly both are amazing.
if you asked me 2 years ago...or even just a year ago I would've said jdramas without a doubt but now the lines between them are kinda blurred. they both evoke emotion in their own unique way. so it's just a matter of cultural differences now ;)