Albania

Verdict:

The Albanian flag has stayed mostly the same for over a hundred years. It features a black double-headed eagle on a red background.

Keep It Simple. The flag should be so simple that a child can draw it from memory…
Use Meaningful Symbolism. The flag’s images, colors, or patterns should relate to what it symbolizes…
Use 2 or 3 Basic Colors. Limit the number of colors on the flag to three which contrast well and come from the standard color set…
No Lettering or Seals. Never use writing on any kind or an organization’s seal…
Be Distinctive or Be Related. Avoid duplicating other flags, but use similarities to show connections…

The complexity of the eagle design sets it back in the first category, even though it is a fantastic design.
The red symbolize valor, bravery and strength while the black eagle stand for Albanian independence. The black eagle on a red background has been a part of the Albanian peoples for over five-hundred years, having it's origin in the mid 15th century and being a central figure in their fight against the invading Ottoman forces.
The country has a unique flag, being only slighly similar to the flag of Montenegro, and it looks great for it.