My horses are out in a paddock 24/7. They have a dam in their paddock to swim/play in, trees for shelter. Honestly, they love it, and I think they would be miserable in a stall. Theres nothing better than watching your horse roll in the dirt after a long ride and seeing the satisfaction they get out of it.
I think I would only stable my horse if I was showing at a national level... I do small shows but rugging them a few days before the show in summer and keeping them rugged in winter is enough to keep them looking schmick. We have a sheep yard that we use if any of them are sick, it backs on to the paddock sot he others can talk to them still, they don't get lonely.