I personally REALLY like that last liver chestnut. Gorgeous head, good shoulder angles, a little long in the back but that's balanced out by a nice long neck. That hindquarter could be stronger but it isn't too bad. The only things I really see are slightly long, over-sloping pasterns, and possibly straight hocks. This horse may be a little over at the knee but I actually like that. As long as it isn't too severe it can actually be a good thing, as it reduces strain on the tendons.
With the $3k horse, I don't really see anything about him that's truly spectacular. He has REALLY nice shoulder angles and a nice large strong-looking rump, but he is long in the back and neck, and perhaps a little light in bone.
They are all somewhat herring-gutted (may be from racing so I will let that slide) and most of them are very long in the pasterns. The dark bay 3yo, in particular, is very upright in the pasterns and also the shoulder. He is light in the neck (I like them with substance, which this guy lacks).
Can't see enough of the black mare to really critique her but she looks like she may have a weak hindquarter. Other than that, REALLY bad photo.
My picks of the bunch are the $3k bay and the 6yo liver chestnut. Of those two I would probably choose the chestnut, solely based on hooves (the bay's hooves are long in the toe and low in the heel). If the bay's hooves were balanced better I would probably choose him but long toe/low heel causes a LOT of problems. Both have relatively short cannons, the chestnut in particular - this is a strength.
They all have their faults and it's up to you to decide which faults you are willing to overlook, and which faults you just can't accept. For me, I can overlook slightly crooked legs (but NEVER back at the knee! Slightly over is good, back is VERY VERY BAD) as long as the rest of the horse is acceptable, and that especially includes hooves. Straight shoulders, long or upright pasterns, and weak hindquarters are never going to help a horse along in any of the English disciplines. They limit reach, make the stride jarring and/or uncomfortable, and most importantly, can (and do) cause soundness problems.