Keun Ruk Salub Chata The ML is conventionally intelligent and successful, the FL not so successful but she has more street smarts. They are both extremely nice, like too good for their own good.
Roy Leh Marnya probably the nicest ML in thai lakorn. Waaay too nice, to be honest, but not a door mat. The FL is equally nice and they both are really successful and competent in their field.
Kill Me, Heal Me they both are smart, successful in their respective field and super nice and cute (but mature, not childish)
Love Is Sweet , the leads are also sweet. They're both smart, though the ML is more successfull but there's a good reason for that.
Lying Heart this is interesting because they both start out nice but something happens and they both start acting like *ssh*les. They also are both equally smart and successful.
Lub Luang Jai this is the nicest, most successful couple I've seen on tv. I swear they are saints or something.