Oy, I think you've just opened up Pandora's Box, Jekka.
I prefer whatever works for the individual horse.
I heart my farrier. He trims as well as shoes, but won't try and upsell shoes for a horse that doesn't need them.
My TB was in shoes all around when I brought him home. Now he's down to 2 shoes in the front. Farrier said he didn't think the horse needed 4 shoes, so we put him in fronts only. He's doing wonderfully.
My riding Arabian is also in front shoes, only because he has a crack in his left front that I want to grow out. Farrier said it's not all the way through the hoof, but I wanted shoes on just in case.
My retired Arabian is barefoot. Most of my horses in 32 years have gone barefoot, and Casper will be barefoot again once the crack in his hoof is completely grown out.
I like to keep them barefoot if possible. If they can't walk sound without shoes, they get them. As I said, it's all about the individual horse and what they need to stay sound and healthy.