I quite like using SwiftKey, its great at fixing my sloopy typing.

But coming out from under my tin foil hat (coincidently I just returned from a crypto-party at the Open Source Developers Conference), I don't trust proprietary keyboards which require internet permissions, because they have access to all of the passwords I type in. I've got DroidWall [0] denying internet access to it, and I can sleep easier at night. The only down side is I can't download new dictionaries if they become available.

[0] - http://f-droid.org/repository/browse/?fdfilter=droidwall&...

Edit: Specified why I don't like them having internet permissions