I would say that the Schumann is difficult, but it all depends on your forte.
Personally I found the Grieg very tough (6-against-7 in the cadenza, and one part after the lyrical section), and the opening of the 3rd mvt was relatively unplayable for me.
Many people here would probably disagree with me on this, but i found Totentanz relatively easier to play than the Grieg, and it was my first concerto... so just experiment and see what you can play best!