So, then, obviously he is of the opinion that this is the penultimate performance of this work - or at least this portion. Well, it's not so odd that conductors would pick their own recordings. Not only because the music would capture what they thought most incisive in that piece of music, but also because they made that music. Thus the enormous emotional connectivity that one feels to the people, time, event, and music are immediately drawn up into mind by hearing the music. It is a powerful and very personal thing for a musician, because so much of their self is invested in their music. Barenboim did the same thing, selecting as one of his desert island recordings the Elgar cello concerto recording he made with Jackie du Pre. It's as much an emotional connection as it is a judgment of the quality of the recording.
Personally, Rattle's recording would not be on my desert island list. But a recording I made back in the 70s would be -- for exactly the reasons mentioned -- the emotional connectivity to the circumstances, people and era in my life that it elicits.