THe second picture is the best for critiquing because it's the straightest shot... He's quite cute and looks just like one of the boys at my barn. (yes, by boy I mean horse).
So....I would probably lean towards the more conformationally "clean" side because there are not too many visible flaws.. He's got the typical prounounced high withers of a TB, but he's got a well muscled body. Maybe his hind could muscle up a little more, but is he jumping sound?? That might be a good way to bulk up a bit back there. (By jumping I mean little X-rails while being lunged or whatnot. Not specifically big 3'6 fences etc. )
He's got a nice neck, and clean legs. I guess that's what I see