I believe this comparison doesn't make any sense to start with, as there are no recordings of Liszt playing in existence, so anything would be just speculations...
On the other hand, even if we were that lucky and were able to hear Liszt play, that comparison still won't make much sense, as we'd compare apples and oranges as besides the obvious fact they worked in different medium, the difference would be much deeper and much more than their technical achievements.
That would be just the fact that Liszt was one of the greatest innovators in the music history, a man who created new genres in music (both piano and orchestral); created new ways of music making, new ways of thinking about piano, completely new way of thinking about piano techniques, completely new way of thinking about piano colors, etc. etc. etc. That's besides the point he was one of the most advanced people of his time, publicist, teacher, a man who completely changed the view of an artist in society, and left colossal impact and has influenced generations of forthcoming composers.
Definitely, none of that can be taken off the scale when making such comparisons... But why should we compare uniques? Isn't it enough to be thankful both of them existed and we just can enjoy their ART?
Best, M