Each have their own qualities but in the end I choose Chopin. And since you didn't provide argumentation neither will I. 
I simply like Liszt's better. To me, as great as they are, Chopin's etudes are much more one-dimensional. They only work on one aspect of technique each, and to me (Chopin certainly does get the most musical value possible out of that dimension) that really limits the result. Liszt on the other hand, in each etude focuses on multiple areas of technique, while still focusing on making pieces of musical value. This, to me, gives the Liszt etudes an added dimension that Chopin's cannot compete with. He had more material to work with, and he took advantage of it.
Liszt's etudes also tend to be much more substantial, while Chopin's tend to be in the 1-5 minute range, most at around 2-3, Liszt's go all the way from 1-10, most around the 5-6 minute range. To me they are more complete, more satisfying pieces of music. And frankly overall, to me, while Chopin's etudes are tremendous, Liszt's are just 'transcendental,' they are remarkable pieces of music that exploit everything the instrument has to offer in creating remarkable, beautiful pieces of music, that transcend what Chopin's have to offer.
Now I LOVE Op 10/3, 4, 9, 12, Op 25/11, 12 (and all of them really), but to me NONE of these compare to the sheer beauty, power, and passion of 'Un Sospiro,' 'Chasse-Neige,' 'Harmonies du soir,' TE 10, those especially, and more.