If you where to ask Rex what he thought of Noah he would have responded with "I think he's an ok guy." Of course inside he held Noah in the highest regard. Noah was great at sports, he was smart and popular (hard combination), he was ok at video games (but that was compared to Rex who secretly cheated now and again), he could always handle himself in a crisis, gave great advice, was fun to be around, and he could even hold off an attacking evo! The dude could pretty much take his job if it wasn't for the fact Rex was the only one who could cure evos. If Holiday ever found a way to make a cure herself Rex would just have to give up in anger and frustration all to eventually hand over his job to Noah.
Although Rex did have a few things that could hold there own against Noah's talents such as his nanites (but personally he decided they shouldn't count since without them he would be an normal guy). Sure he had his humor and good looks but his personal achievement would have to be his height because it is the only thing Noah hasn't been able to touch, yet. Noah could get the skills to beat him but Rex was always the taller of the two. So every now and then Rex would just have to make fun of Noah's height (and every time he did Noah would hear just a touch of jealousy in his voice).