It's a very long time since I was a teenager and I probably can't remember half of them.
Murder at the Vicarage was the first I read. Then The Mirror Cracked form Side to Side, The body in the Library and A Murder is announced were some of the early others I read. I used to read one then go into a book shop and just get really excited about buying another one. It wasn't easy to know much about what was coming out next in those days. As I said earlier, I always preferred Miss Marple but I liked the Poirot too, just not as much.
I can't really critique them, I was very drawn into the country house way of living and wanted to marry a vicar back in those days. Miss Marple sort of took me there