What piano piece should I learn next?

[pianoperson2008]

Recently I have learned Chopin's Étude 10 no. 3, Étude 25 no. 7, and his Waltz 64 no. 2 (which took much less time to learn than the other two). What piece do you think I should learn next? I'm partial to pieces which are unhappy or angry, and maybe a little challenging.
Thanks in advance. 

[droprenstein]

This is extremely vague. It's hard to give such an estimate because difficulty is so subjective. 25/7 and 10/3 are both some of the easiest Chopin Etudes, so we can't say if you can handle some of the others. If you can handle those two, you should be able to handle 25/2 and 10/7 as well. They're some of the easier etudes too.