I think the current American IR books are the best for serious IFR stuff.
I found Richard L Collins's books invaluable when I was learning (almost 20 years ago now). I imagine the underlying principles are still as true as ever, even if the details have changed a bit. But they are focused on what you might call "serious IFR".
Here's one for example. Can't argue with "One of the primary tasks in instrument flying is to get priorities straight in your mind ..." can you?!