I'd go ej257:
-Both do not have forged pistons...ej257 pistons are stronger imo.
-extra displacement of ej257 (you won't rev out the ej22 anyway with stock wrx heads)
You won't reach the point where you need a closed deck. With an ej257 you get better piston design, more displacement, newer crank design, and they are readily available and are proven to make good usable power if tuned well. Now if you are building a motor that is a different story.