I board at a high end training barn with about 20 horses/12 boarders and our trainer owns the farm. There are one or two people who come in just for lessons, but it is overwhelmingly for boarders. The horses are all high level dressage horses with one or two young prospects and are worked 5-6 days per week either by the horse owner or the trainer. They get unlimited hay, 3 feedings a day including supplements (always soaked), blankets, boots, stalls cleaned twice a day, holding for vet and farrier, daily grooming, etc. Our horses are taken care of exactly like the trainer's horses are and you could really spend your whole riding career there without ever knowing how to take care of a horse, which I know sounds awful to some people but it speaks to how well they take care of everything. Everyone is supportive, helpful, and fun but we're also all very serious about our riding, whether we show or not.
The only drawback is that we only get 4-6 hours of turnout a day, 8 on a really great day, and we only have quite small paddocks. Considering how we work our horses it is not so bad, but I wish it was more. Almost all of the horses are turned out individually, although thankfully my own horse goes out with a friend. But there are no high level dressage trainers in my area who do more than that anyway so you take what you can get.
That is what matters to me when considering boarding - care, training, relationships with other boarders. In terms of aesthetics, of course it is fun in a ridiculous way when stables have chandeliers and that sort of thing and I wouldn't want to board in a hovel, but in general aesthetics are not important. I do want the horses to be able to stick their necks out of their stalls and greet each other over the walls. And a bright, airy arena with mirrors is very important to me. I find dark, windowless arenas past their prime to be very depressing. I would never want to be in a lesson barn and I would only board at a place with mostly adults.