Please suggest a good edition.
My personally recommended editions of Chopin Etudes are:
- Wienner Urtext. Edited by Paul Badura Skoda. Very reliable text, very well researched, with several variants, original Chopin's official fingerings plus fingerings found on pupils' copies. Badura Skoda's fingerings are also very good and there are also a few fingerings from other great pianists such as Cortot.
- PWM Polish National Edition. Edited by Jan Ekier. With very similar qualities to Wienner, but with even more variants and original fingerings, and with a big clear text and the invaluable fingerings of Ekier himself.
I would not recommend the Paderewski ed anymore, although I've use it during several decades. They made quite a few weird editorial decisions and changes (too many for an urtext...) and IMHO there are (far) better fingerings than Paderewski's out there.
Regarding old editions such as Mikuli, they can be used as an occasional reference;they are not devoid of interest (as all of you know, Mikuli was a direct student of Chopin) but in my opinion they must be taken with a grain of salt. This and other similar editions (Klindworth, Sholtz) should not be used as a main study text as they are not free of editorial random changes.
Regarding Henle, that's one of my favorite editions generally speaking but I'm not quite personally fond of the fingerings they put on the Chopin Etudes edition.
I also would recommend to own Cortot's edition. Again, not as a main source for study but for further reference. The preparatory exercises deserve a look at least and there are some interesting fingerings. Not that you must use all of them but some of them are really revelatory.