There are two riding schools within a reasonable driving distance of me. I have friends who learned at both. The nearest one is downsizing - they only run lessons a few days a week, I saw their outdoor arenas and they were run-down with broke fencing, and the horse-walker clearly hadn't been used in years as the weeds were three feet high in it! Horses stood in small stalls that weren't level and the buildings looked very run-down, including some with broken roofs. A friend who used to ride there told me that old horses, or those with long-term injuries, were sold off - sometimes to the meat man.
So, naturally, I chose the other one. It's more expensive, but they have clean, new facilities with an indoor arena, outdoor arena, and lots of stabling. They're what we call 'American-style' stables - a big barn under which it's all assembled - with loose boxes, stalls, pens, the office, tack room, a sort of classroom for more academic teaching, a shower/washroom for the horses, and so on. The fields all have proper fencing - no barbed wire to be seen - and the owner trains showjumpers, so there are a lot of good quality horses there. I also know that they take care of their horses when they're old. One of their founding ponies, a mare called Black, was being ridden by a friend about eight or nine years ago. Black was twenty-seven then, and still sound. She did gentle work with young beginner riders. Later on she was completely retired, and died of old age last year.
The instructors I've met so far are all great, and one of my friends used to board there until she found a livery stables much closer to her home. While she wasn't fond of some of the people there, she told me that they always took very good care of her horse.
I'm glad I chose the stables I did, because I wouldn't want to support somewhere that didn't have responsible practices, both in teaching and horse ownership. I've also heard horror stories about some of the practices at the other stables - pushing beginners into things they weren't safe to do, unsafe riding environments, not replacing hats after falls and so on.
I don't know much about horses and riding, but I did try to think about all of these things. It wasn't a hard choice between the two schools, but I wanted to find out as much as I could about their practices before I started riding. While I don't have to take care of a horse myself, I'm indirectly responsible for their care through riding at that school, so I wanted to go to a place that took care of their horses properly. I know that I'm very lucky that my dad lets me drive his car and doesn't use it to go to work, because otherwise it'd be a choice between the poor stables (just within cycling distance) or no riding at all.
Oh, and I've just found out that time Times named it as one of the eight best riding schools in the UK, and the owner's trained Grand Prix dressage horses too. Heh.
So, how did you choose where to ride or board your horse?