Op 25 #7 is manageable to most grade 8 level players. Op 10 #3 is also a good one to start with, but unless you are comfortable with 6ths, you may struggle in the middle. I would echo what has already been said and pick your favourite and learn it correctly from the beginning. All the etudes will be beneficial to your technique so none will be wasted time and effort.
Just going through the ones I played, 10/1 everything falls under the fingers easily, except for the awkward passages (trust me you'll know what they are) which are absolute hell to play. The whole thing is extremely difficult to play clean. Same with 25/1210/4 one of the more difficult etudes, top 8 at the very least. It's a workout for both hands and any lack of dexterity in either hand comes out as a mess. The impressive coda is the easy part..10/5 not very many issues except right before the main theme comes back and the octaves at the end. Everyone fakes those anyway..10/7 its easier than it looks at first, but later it gets tiring and relaxing isn't exactly easy.10/8 its much much harder than it looks, especially the middle section10/12 good left hand workout, some issues in the right hand, but if you have good octaves, they won't be much of a problem.25/1 sometimes you don't "stretch" far enough to hit the right note, but otherwise not too bad.25/12 just plain tiring. Easier to clean than 10/1 imo, but much more tiring. hope this helped