My list is of Top 10 active pianists as of 2015.
It excludes the retired (Brendel) the semi-retired/conductors (Ashkenazy, Pletnev), and the once-great but no longer (Pollini). It also excludes Zimerman and Sokolov: I have never seen them live, and given that they barely record, I therefore can't assess them.
1. Leif Ove Andsnes. Having completed his "Beethoven Journey", he is at the peak of his career and the peak of the profession.
2. Maria Joao Pires.
3. Martha Argerich. Would be even higher but for the fact that she's not really extending herself as a soloist at present. Still, couldn't put her out of the top three. Recent live recordings with Abbado and Barenboim were exceptional.
4. Daniel Barenboim. Like Ashkenazy and Pletnev, very much a part-timer. Except that with his extraordinary work ethic and prolific production, he gets to make the list. His recent multi-disc recording of Schubert sonatas - where does he get the time? - illustrate that he still belongs here.
5. Nikolai Lugansky. The top Russian, in my view. Recent recording of Grieg/Prok 3 was superb.
6. Marc-Andre Hamelin
7. Nelson Freire
8. Stephen Hough
9. Jean-Efflam Bavouzet
10. Arcadi Volodos
Tough to leave out Perahia and Anderszewski. Lang Lang would also be in my Top 20 - he, his facial expressions and his PR machine all annoy me but you have to respect his ability. Only one Brit in the top 10: Hough. Full respect for Uchida, Lewis, Cooper, Hewitt, Osborne, but I reckon their careers get aided by their nationality (not their fault) and aren't Top 10 material.
Levit, Fliter and Yuja Wang would hopefully have strong claims in the near future.