all white keys is easy to play a scale without thinking, but I find it much harder to play well than keys that have some sharps or flats. that pattern of 2-space-3-space on the black key shelps to anchor your hands. I'd take e-flat major--its far easier to play than c-major.

Transposing is harder, but the vast majority of piano litature is never played tranposed--you play the notes on the sheet music. I've tried some of those new layout keyboards like the Linnstrument, and I'd never try to play a Beethoven sonata on one.