I haven't read all that many, but I think the two recent light-hearted ones would be the favourites, Henchmen and The Band Sinister. Her other books I really like are A Fashionable Indulgence, A Seditious Affair (going to read part three soon), A Queer Trade and An Unnatural Vice, which I read completely out of order (because it was discounted). The ones I did read and liked less (although they were still good) would be the first Magpie book, the short story about Ash and The Price of Meat.

There is a chance The Magpie Lord will grow on me on second reading of course, but there are all those others to try first and anyway it depends a lot on prices, friends with copies to lend and so on. I might not have that much to compare her books to, but I have read one historical m/m romance by Cat Sebastian, one by Lee Welch, three by Joanna Chambers and two or three more by other people, and all of these are just worse? Various shades of pleasant, but much less so than KJC. :)