My list of cosies includes Ngaio Marsh's Death and the Dancing Footman, Lesley Cookman's Murder at the Manor, Hazel Holt's Lilies That Fester and, of course, Dorothy L Sayers' The Nine Taylors and Gaudy Night. I love all of these writers and have read and re-read Sayers' novels many times. For me Ian Carmichael was the definitive Lord Peter Wimsey.
I'm also a great fan of Veronica Stallwood's Oxford novels and wish that she would write some more! I might find time to slip in a couple of M C Beaton's Hamish Macbeth's novels if I have time.