It's difficult to judge SEs on ethics. And, ethics vary from culture to culture.

Is hand editing of politically sensitive issues ethical or non-ethical? What about using personal data without permission as long as it's to improve results for the user?

Based on my personal view of what's ethical I'd go with MSN... less invasive/intrusive* than Google, less obfuscation* of commercial results than Yahoo. But then there must be lots of smaller SEs that are a lot more "ethical".