I mean, you've got the body resized at 200%, and the wings/tail resized at 100%. That looks wrong.

Your sprite should have the exact same little detail no matter what size it's at. Otherwise you're going to have some compatiblity issue or other, even if it is "why are your pixels bigger than mine?".

Plus they use different graphic styles... black line shading vs. smooth Nick Stadler shading. No contest, but not a perfect mix.