2431 for me.
2 only problem area is rear legs, maybe an under-muscled neck. Good carriage and neck set, short back and nice forehand with a decent rear end for an engine. Not as slicked up as the others, but nicer horse overall.
4 is pretty, but has a long back, long pasterns, is hip high and maybe a touch weak on the forehand. (Over at teh knees?) Overall good looks, like a young hunter-under saddle prospect,
3 is well built , good back, shoulder and hips, good forelegs, rear legs look to be (uhm.. getting old is a pain, slightly cow-hocked. And upright in the pastern, front is a little base wide, probably from the low neck tie in. Also is heavy in throatlatch, and goose-rumped. Probably comfortable to ride tho.
1 is the result of overbreeding. Straight pasterns, long back and thick stance will make this horse a nightmare to ride. Pretty as he is, he's weak in the throatlatch, and too straight behind.
If I was buying these horses.. the order would change slightly to 4231, as I like the bottom buckskin myself )