Because This is My First Life (their kisses are quite tame though)
I Need Romance 3 (it takes a while for the main couple to officially get together, but they kiss before that, and lots of other characters kiss too - virtually no peck-on-the-lips kisses or frozen kisses)
If you're willing to try some non-Kdramas too:
Sound of the Desert (Chinese)
In Time With You (Taiwanese - mainly the last episode)
As for "regular" length dramas, The Reply Series (probably '94 is best with this), Coffee Prince, and Secret Love Affair are ones I recommend, not just for the kisses, but realistic depiction of skinship~ in relationships. But, tbh, my favs for this are longer dramas wherein couples usually get further than just dating (actually in the former two mentioned above the otps marry but not much of after-married life is shown so), and thus have more instances for kisses/skinship: Glorious Day, Heard It Through The Grapevine (I honestly rec this one so much, one of the best dramas ever imo), ummm What Happens To My Family, Ugly Alert......etc.
Thank you guys soooo much!! Your responses were so good that I've actually seen a lot of these lol. But the ones I haven't seen I will definitely look into including the non-kdramas and the long ones!!