Who is the best classical pianist alive?

Why always this puberty like best - fastest - highest? This may work in sports but never in art!!
I agree to your above list but I think the following are missing: Hélène Grimaud, Lang Lang, Volodos, Uchida, Brendel, Hough, Lewis.......and some more.
Whether Pollini is the best depends on the music - f.e. NOBODY plays the Schumann concerto like Grimaud and NOBODY plays Tschaikowsky 1st like Lang Lang. The question if this is THE BEST is obsolete because as I said above - art is above such measures.

There you have it: Lang Lang is morphing into Bang Bang - a rather ignorant thought - but people are different.
Talking of some won competition: we certainly forgot Ivo Pogorelich on the list who - as everybody knows - did NOT win and Martha Argerich subsequently left the jury....
Being a pianist myself I only can subscribe to what Czbbcl wrote and what I mentioned in my first answer to this thread.