The real determining factors on who will be considered more advanced and the better pianist are things like:
How big is his/her bra size?
When bra size becomes any kind of determining factor for a male pianist, critical traditions and appreciation will have undergone quite a fundamental change, I humbly submit...
How much of his/her boobs show at any given time?
The extent to which his/her wrong notes and other performance errors become apparent will remain a matter for the critical faculties of the listener.
Might one "pop out" unexpectedly while playing?
Audience members do occasionally walk out when a performer is performing, usually when the performance is hopelessly inadequate, so I suppose that this might continue in such circumstances.
How well can her/his boobs play the piano?
This question takes the clichéd notion of Liszt playing the odd note with his nose to interesting but potentially quite painful extremes...
Is s/he generally sexy? Super? Kind of? Not really?
That's something for the eye of the beholder that will count for nothing in a recording where the more necessary ear of the beholder is the only critical facility.
What kind of clothes does s/he wear?
When? While performing or while involved in other "non-concertizing" (see, I know my American!) activities?
What color is her/his hair?
And isn't a good thing that Arnold Schönberg was not a pianist?
How long or short is it?
How long or short is what?
Are they generally considered to be attractive-looking?
Are what considered to be attractive-looking? Are you back to those boobs again?
Would you want to sleep with him/her?
Leaving aside the fact that "sleeping with" anyone is a generally accepted euphemism for doing something with them that would not be expected to involve soporific inactivity, I don't suppose that anyone would really want to sleep with anone while they're playing the piano.
What color are his/her eyes?
It would be difficult to determine this from the auditorium, especially with the pianist facing at right angles to the listeners.
Do you generally approve of his/her set of buns?
Buns? Quoi? OK, here's an Americanism that's tripped me up after all; since the art of the patissier is clearly not something to which you intend reference here, I appear to be left with little option but to admit to having encountered yet another instance of two nations divided by a common language.
Best,
Alisair