Of course, there's no one definitive answer, but if you'd like to see a good side-by-side comparison, compare Witch Week by Diana Wynne Jones (Pantser) with Chamber of Secrets or any of the other middle Harry Potter novels by JK Rowling (Plotter). I suggest these two because they are both modern British children's fantasy novels about magical teenagers at boarding school, so you can really isolate the differences based on writing approach. Jones' books are more creative and anarchic, at their best they are absolutely magical (so to speak) and weightless. But they tend to fall apart at the end, with weak, hurried endings and lots of deux ex machina and hand-waving. Her series also suffer from a lack of focus and continuity.
Rowling's books are tightly plotted and purposeful, with mostly satisfying twists and turns. The Harry Potter series as a whole has a sustained plotline and successful larger character arcs. The endings usually seem earned, and everything fits together, for the most part, like a well-oiled machine. On the other hand, while they were lauded as fresh and original by people who don't often read children's fantasies, people who know the genre noted a lot of cliches and tropes. Rowling herself has admitted that her preconceptions sometimes prevented her from making the right character choices. And in the cases where the planning didn't quite work out, it is much more noticeable and less forgivable.
Personally, while I like both, if I had to choose just one, I would go with Jones --I find more that's new and unexpected to discover in her work. On the other hand, she has far more duds than Rowling --the quality of her writing fluctuates wildly, whereas Rowling is a reliable good read. For two other examples drawn from my own writing heroes, Haruki Murakami is another admitted Pantser, whereas Samuel Delany, is actually a Plotter, although his work doesn't always seem like it. They both tend to write with a dreamlike, surreal, unexpected quality, but you can still apprehend some of the difference in approach in the final work.