Ima Cool Rookie seems a tad ill-proportioned to me.
Lilly has nice, straight legs, and a great pedigree.
Jackie O has nice legs, well proportioned.
Count The Loot has nice legs, but has a pencil neck, which I personally dislike.
AMD Steel James is flashy, and looks like he has a great build for gaming, unfortunately the pictures they have of him make it hard to know what his leg conformation is like..
All in all, Lilly seems like the betst choice out of them for halter conformation wise, but AMD Steel James will catch the judges attention, and in a crowded class with 15 other horses that can be a really good thing. It also depends on whether you would show them halter and sell, or keep the horse afterwards.