Superdonor conveys a feeling of superiority, as in better than other donors. In other words, even if you donate less, if you donate more effectively, you can still be better than other donors by donating more effectively.

My personal preference is that you promote honorable reasons for donating, while recognizing that dishonorable reasons exist. Donating so that I can feel superior to other donors who give less or give differently does not strike me as particularly honorable. I admit that I am using the term honor without ever having given much thought as to what it means.