Please the book about Wallenstein's army.I was not impressed by Spring's book about the Bavarian Army, which suffered from Pictures of Bavarian troops (I think there was not one picture with an ordinary Bavarian soldier!) and I had not the impression, that the author really looked deeply in the Topic, many chapters didn't really mentioned anything about the Bavarians. I would fear that the book about Wallenstein's army is much the same, as Spring often told more about the Imperialists than about the Bavarians. In my point of view it would be better if they would rely on somebody, who can do Research not only in military but in local archives too... Therefore please the book by Laurence Spring.
I agree the Bavarian book was disappointing but his others have been fine imho.