Which app is best for MSN/Yahoo messaging on Android?

Best in the sense of: Stable, minimal/no errors or problems, minimal memory footprint.

Lotsa names mentioned online, but first-hand feedback from users here would be appreciated

Any app that can password protect a file or folder?  Found some on the market but not sure if they're reliable.

Also, any messenger app that can customize background / skin?  Am currently using eBuddy but don't like the background color or how it overwrites my display message (any way to disable this?).