I have. I really like the technical aspects of WP, and the show ring strategizing. I love the adrenaline of barrels, and making everything come together to get that great run. I firmly believe that doing both has made me a more rounded rider.
I've done both and I really like both. I can't really compare because I started on two different ends of the spectrum. When I started showing Western Pleasure I had to work and get my horse going as she was not trained right and the people before me just let her plod along. However when I started barrel racing my horse was finished and for the year I competed on her it was a great learning experience. Now my barrel horse was patterened just needs seasoning and my show horse I use now just needs assistance to make sure he isn't four beating. Now that I went way off topic, like I said before I really can't compare them because showing helped me have nice quiet hands and seat but I had to gain the confidence to go fast... I still do both, so I can't tell you which one I love best!