Dragonstar

Not sure if this is the case in all editions or not, but the edition I read included a summary of the first three books before the book properly started. The tone of this book is much closer to the original Dragonsbane, so here's what I'd actually recommend:

If you like Dragonsbane and want to continue, read reviews for Dragonshadow. If you think that book likely isn't for you but still want to read more of Jenny and John, skip straight to Dragonstar. You'll get the summary of what happened in the previous books, which is enough to understand the story.

Full disclosure: I did enjoy the two middle books (most people seem to regret reading them) but they were hard to read at times. The content is very dark, which I knew ahead of time per a review - but even knowing that, I had trouble at points. I do think the middle books are good (I loved seeing more about how dragons think, especially compared to Morkaleb), but they are definitely not for most people and will leave you hurt. Dragonstar does not.

This book does talk about some of the darker things that happened in the previous two, but not quite as harshly, and there are more good feelings in general. This is still a book about demons, though, who continue to do what demons do. So if that whole concept is upsetting for you, then just read Dragonsbane and leave it at that.