I had a mini barn built, 4 stables, 2 facing each other each side plus a tack room at the end. Its fab, the aisle is very wide so no bullying, and the horses have stable doors into the aisle plus half (top) doors to the outside so they get fresh air and views. When those are closed they have barred windows in the middle so the horses can still see out even if the main front door is closed in awful weather. It is lovely and snug in there but instantly coolable with these doors/windows, and its far less dusty than their old livery looseboxes, partly cos the top of the stable is the roof of the building, so no cobwebby rafters, and partly cos we use aubiose/wood pellets.
They can see each other but not bug each other, and I dont get wet mucking out more than necessary, and my radio stays dry too!
They adore it. We are in the Cairngorms so needed something where we could batten down all hatches and it has proved just the job.
I think the best stables are:
1 Very good mini barns
2 Normal stable blocks
3 Very large american barns / one with no outside opening windows/ones badly converted from agricultural sheds