Interception, honestly I'd say gunnery and here's why.
Piloting is nice, but it doesn't do anything for speed. Also, based on what I remember, there's not that many PSR except for damage rolls and the like in space.
However gunnery will allow you better chances at crippling the enemy.
An inventive GM could say "sure do some crazy barrel roll to get out of a tight spot, Piloting roll please."
But based on just how the books play it out for space battles, gunnery would be my priority at least.