A lot of interesting / likable / memorable / funny characters

Is your list up to date?
I'd recommend you to watch the currently airing "Beautiful Gong Shim" - both of them are quite funny and such dorks... Especially the main lead, I think you can't help but love him. :)

Marriage, not dating ^^

Dramas with many funny, interesting characters:

Hana Kimi (beats everything else)
Atashinchi no danshi
Reply 1988 (& 1997 too)
Love Shuffle
Yamada kun to nananin no Majo
Sugarless
Pinocchio (The reporters are funny awesome)
Ex-Girlfriend Club
Cheer Up

Not funny but interesting & memorable:
White Christmas
Shut Up
Incomplete Life

Recent ones like DOTS, Come Back Ajusshi, My Little Baby also fit, I think.

I second Please Come Back Ajusshi
Others:
Date - Koi to wa Donna Mono Kashira
Kokoro ga Pokitto ne
Kaitou Tantei Yamaneko
Love Shuffle
The Lover

I hear your voice, has great main characters, the supporting cast is also quite loveable & funny
Splash splash Love (webdrama) has really cute and loveable main characters. 

These have been suggested already, but I'll mention them again because they're so great:
Hana kimi (first Japanese version)
Sassy Go Go/Cheer Up
Reply 1997
Page Turner (webdrama)