Clifford Curzon for #20...Conductor is composer Benjamin Britten..
I've listened to most all of them, and it is my hands down favorite.
Under Britten's baton, the orchestra playing is equal to Curzon's sensitive piano playing.
Many times orchestra playing is an after-thought. The orchestra and soloist really perform together here; unlike many recordings where is sounds like they are just taking turns playing.
Get the budget 2-CD set that has 20, 23, 24, 26 & 27. They are all excellent, especially #20 and #27...
If you want a second opinion on these recordings, read this.