My recommendations are No. 9 (K271), No. 14 (K449), No. 17 (K453)--all three about similar difficulty, and a little easier than the others.
-Slightly less great: 19, 26
No. 15 (K450), Nol 22 (K482), No. 24 (K491)--C minor, and No 25 (K503) C Major--difficult.
Im learning 15 at the moment! even Mozart said at the time of compostition anyhow "it'll make you sweat!"
I only started it last week, but it's got some awkward scale passages - trying to get them smooth shall be rather fun!I was reading that "it gives quite exceptional prominence to the soloist, in long sections of bravura which re calculated as part of the organic growth and not inserted as mere display".This sort of analysis is not my strong point so i'm not exactly sure but I lik it obviously.