I say only the OP can answer the OP's question. Plop your hand down on a mock up and see where your fingers naturally land and want to move, thats where it needs to go.
Top row or bottom it wont matter, your layout has the same degree of tilt for both rows so they are identical in use, so it would depend on your arm position more.
I went with the traditional JP layout and moved the joystick further away, its much more ergonomic than the straight SF style. Though seems my 1st and 5th button came out abit close for some reason.