You want something that is built "uphill" . With a lighter front end but a stilll powerful hind end, you want nice clean, straight legs, with no interference with the other legs and hooves. A neck that is well muscled, set well but isn't proportionally to long, you don't want a long dipping back either, but you also don't ant a mutton wither or straight back.
You don't want a horse tht is "heavy on the forehand/heavy in front" this will be harder t oget back on the hind end to gain that forward propulsion/engagement/lift to get you over jumps.
This all doesn't matter "that much" at lower levels and learning.
But if it's your very first horse, it will a. Be hard to part with . Get most of the training at some expense. So you want something that's not going to break down, be physically unfit for the job, or be predisposed to becoming injured/lame/incapable of the job at hand.
Horse numer one. If he really isn't the down hill, would make a nice light hack, he is refined enough, with nice chrome. He needs to be let down and gain some muscle, weight and top line. Ut that wont change the angles of the pasterns (too upright) and 6 years he's pretty much done growing. Don't get me wrong nice ooking horse. But not right for the jump job IMHO
Horse number two is slightly sickle hocked, and higher in the rump then the forequarters. She's nicely built in the front though, her head and neck tie together well, same with the shoulder and neck, she has a large chest for heart/lunge room etc. But her front legs seem to built a little maybe back at the knee or underslung in the heels not sure the gravel makes it hard to see clearly being white/grey haha. She seems very upright in the offside front leg.
My ultimate pick of the two is the gray, hands down, she is much sturdier built nd you can't be all that choosey with horses, they aren't 'perfect'.
I'd definitley pick her and pass the black/brown on ;)