Some of Agatha Christie's are hit and miss, but some are excellent. Towards Zero sticks in my mind, which was beautifully done, and A Murder is Announced. And The Mirror Crack'd. All superb.
The problem I am starting to find is that once you read a certain number, the various tricks and tropes get easy to spot. But that's all part of the fun, I suppose.
While I love the Sherlock Holmes stories to read they are terrible, terrible mysteries. Leave you thinking
Caroline Graham writes a decent mystery (the DI Barnaby books. Yes, that one, from Midsomer Murders).
In my view, a good murder mystery should end like a decent twist in a film; you don't see it coming, but when it comes, not only does it make perfect sense, you see everything that's gone before in an entirely different light.