Piano Forum

I’ve been playing piano for quite a while now (9 years) and I want to improve my repertoire by an Etude or a harder Nocturne. The two that I would really love to learn are the opus 10 no 3 Etude, and the op 48. No. 1 nocturne. I realise that both of these require similar techniques in their main themes (elevating the melody above the harmony) and that both have fast passages in the middle, sixes in the Etude and octaves in the nocturne. I am uncertain which would be the better option to start with.

My current (higher level) repertoire consists of:
 - op 9 no 2 nocturne
 - Fantasie-impromptu
 - second movement from Beethoven’s pathetique sonata (which also deals with the technique of rising the melody above harmony).

I found these pieces somewhat easier to learn than what I expected, especially the impromptu, and I want to challenge myself further.  I do enjoy playing fast octaves, but I’ve never dealt with sixes before. If you could help me decide which one i should learn, that would be great, thanks. 
Also I would love to here suggestions for any other piano pieces that improve my repertoire, and tips for those pieces would be greatly appreciated  .