you make excellent progress! Of those you've listed, which appear to be pretty much all of them, Gaudy Night is my favorite, because I love Harriet, but I love Peter too, so I also have a Peter-perspective favorite, which is either The Nine Tailors or Strong Poison. I'm very fond of MMA and CoW too but I think they're uneven, comparatively speaking.

this reminds me, time to go catch up on CoW at Listen Again! *dances*