For the first one, it's filled with text and is in need of brightness, Bell's no dark-sided man.
or For the Cena-Orton one, it's clearly visible that Orton's rener is a bit darker than Cena's which reduces the quality, I believe that a simple render-flare (or lightning) would have done the trick. The CR7 one is now looking great but now in the new version the red looks much intensified, was okay in the previous version. The last Bell one looks too simple, it needs much more effects and vibrance needs to be played with a lot as well. That sort of avatars don't look good without a text so I suggest you to have a simple text in such avatars (where a part of render is the focal). Keep it up mate.