Thanks to everyone for their input. I was unaware of an Arrau edition and seeing as his interpretations are wonderful, I'd love to obtain these - one user said they were close to Urtext editions!
I have the Schnabel edition which I think is excellent - it offers fingerings and suggestions for difficult matters of interpretation. I never spent too much time on the classical repertoire so these matters are of special interest to me.
I also have the ABRSM (Edition Barry Cooper) edition which is great if you're looking for the complete set, as it includes the first 3 sonatas which were published in 1783 as a set. I'd like to note that the edition is wonderful for historical information - meticulously researched.
Each volume - there are 3 - includes a small supplement in the back (Commentaries) which discuss each sonata in a bit more detail as well as addressing some interpretation matters. A CD Guide is also included for each volume.

What these volumes do NOT include are fingerings, and I know many wish to have expert fingerings on the scores to facilitate the learning process but that is not the case here. Overall, it is a great URTEXT edition as it relies heavily on original sources.