i studied kabalevsky no 3, really loved it. so many great themes and ideas , very well constructed. i like the other two but not quite as much, no 1 is very reminiscent of prokofiev imho, so that one intrigues me more than no 2.
i think if i go very modern in the future i might want to have a crack at the leonard bernstein sonata, just got the score recently , looks super cool.
and kapustin, yeah any of them, all of them, you name it. love them all!