His piano songs are amazing. Chopin was such talented man.
Although I personally prefer Chopin, I have to say that his contribution to music was a bit too limited because he composed nearly exclusively for the piano. If you only consider piano music, however, Chopin is clearly greater, since half of Liszt's piano output is showpieces (Don Juan, transcendental etudes, Grand galop chromatique, etc.) which may be important in the development of piano technique but less so for musicality. Chopin, on the contrary, wrote no shallow music for the piano. Even the easiest mazurkas have musical substance to them.