I enjoy the work of some of the past writers like the writers of the Campion mysteries (Margery Allingham, her husband, and a neighbor [Mike Ripley] after the couple died); and Patricia Moyes for "Dead Men Don't Ski" and "Johnny Underground."
Dorothy L. Sayers's novel "Murder Must Advertise" has her wealthy detective working successfully in an ad agency to solve a crime. It is a fantastically good time.
I enjoy all the Hercule Poirot mysteries, the John Creasey "Toff" series, and Rex Stout novels.
Many of Lillian Jackson Braun's "Cat Who ..." novels were good until the last couple in which she had trouble writing because of COPD.
Michael Bond wrote the enjoyable comedy-mysteries of Monsieur Pamplemousse. (Bond famously authored the Paddington Bear stories.)
I do like some more modern mystery writers, especially Sue Grafton, Carolyn Wheat, and M. J. Trow for his comedy-mysteries about Inspector Lestrade.