My top 10....hmmmm......let me think.
Well, I'll start with a few of my all-timers, and see where it goes. Although I like some better than others, these are in no particular order:
1) The Awful Truth - 1937 Directed by Leo McCarey. Starring Irene Dunne and Cary Grant.
2) It Happened One Night - 1934 Directed by Frank Capra. Starring Claudette Colbert and Clark Gable.
3) Arsenic And Old Lace - 1944 Directed by Frank Capra. Starring Priscilla Lane and Cary Grant.
4) His Girl Friday - 1940 Directed by Howard Hawks. Starring Rosalind Russell and Cary Grant.
5) Adam's Rib - 1949 Directed by George Cukor. Starring Katherine Hepburn and Spencer Tracey.
6) Born Yesterday - 1950 Directed by George Cukor. Starring Judy Holiday and William Holden.
7) Sabrina - 1954 Directed by Billy Wilder. Starring Audrey Hepburn, Humphrey Bogart and William Holden.
8) The Philadelphia Story - 1940 Directed by George Cukor. Starring Katherine Hepburn, Cary Grant and James Stewart
9) Roman Holiday - 1953 Directed by William Wyler. Starring Audrey Hepburn and Gregory Peck
10) The Lady Eve - 1941 Directed by Preston Sturges. Starring Barbara Stanwyck and Henry Fonda
I have several honorable mentions...most of them filmed more recently than this list...movies like Moonstruck, When Harry Met Sally, Annie Hall, You've Got Mail (and The Shop Around The Corner), Amelie, My Man Godrey....etc., etc.