my3boys, I’m such a huge Jane Austen fan that I struggle to find books as good as hers. And so it is really a challenge to recommend one above the other. They’re all so good. (oh, please do read one yourself, they’re a treat)
Whilst P&P is certainly more often recommended, I would go probably go with Emma. It is difficult to explain, but I think in Emma she draws out and develops her character of Emma beautifully.
In P&P there are lots of themes, and I think it’s plot is more intricate and involved.
You can read an interesting answer to a similar question here, and you’ll find links to other discussions around the various books she wrote on that page.
You’ll know your son best.
Hope that will help and that you’ll excuse my enthusiasm. I can’t wait to share these with my children one day.
Lindy