hey there, welcome to the forum! hope u enjoy discussing...
as for your question....really depends on the mood~ each one has something different to offer
Korean
- very dramatic, more romantic...sometimes character development is there and sometimes the plot can be amazing...but more so, i watch for the romance aspect...
ie. coffee prince, boys over flowers, goong, my girl, full house etc...
Japanese
- story, story, story...if u want to watch something with depth and deep emotions, great character dev. or just plain mind boggling then Japanese dramas are it....i watch them if im in the mood for something different, original and refreshing..not mention they're short!
ie. 1 litre of tears (all time fav), bambino, kurosagi, vampire host, LIFE
Tawianese
- silly, funny...comedy....very lighthearted...If im in the mood to watch some fun-loving nonsense, female leads behaving oddly or just awkward comedic moments then i'll go for these....i haven't found a "deep" taiwanese drama..ever and i've seen alot lol...
ie. fated to you love, hana kimi, devil beside you, iswak etc..
Thai (i know it wasn't an option but i thought I would mention it)
- very heavy on the romance....not deep at all, nothing too dramatic and can be silly at times....always always has a romance angle which is very heavy on physical closeness and jealousy..hence i've im in an extremely mushy mood with some nonsense jealous throwin in...i'll go for thai lakorns (dramas)...
ie. defendant of love, jai rao, sawan biang, botai gleep sudtai
^ threw in a couple of examples incase people were interested =)