As I’m currently playing on Treebeard, finding good armour appearance is a bit more challenging! There doesn’t seem to be a visual database of all available armour which is easy to compare looks. The wiki is incredibly informative and generally includes appearance, however you need to know which item you are looking for and they are on individual pages which can make searching purely for appearance a little tricky.
I’m going to screenshot the most likely sources: skirmish vendors, barterable armour sets, crafted and possibly some vendors. I will exclude Festivals (as FibroJedi already has an extensive appearance database for those) and also drops / quest rewards (as that would be a mammoth undertaking and many are just recolours…)
The armour is up to level 50 currently as I’m playing on Treebeard. I will update this page with links as I post them.