The Ermor flag is just about the right size. I like it quite a bit better than the normal Ermorian flag (I don't particularly like big purple or blue or red blotches with ugly pleats in it on the map).

The Abyssian flag needs to be toned down or made a little less 'vibrant' or the edges more blendable.

The Pangaea flag is too big and by big I mean tall. It doesn't fit in the Messages field very well. It's kind of vibrant (like the Abyssian) I think it would be better a little toned down.

Note: I looked at them singularly and having an empire of about 15 provinces on each to try to see if it created eye strain. Only problem I really had are with what I noted above. I played on Aran and The Desert Eye. As I like that visual flavor of map more than say, The Sundering. I'm of the same opinion when looking at it on "World War" too.