IMO row 12 is the absolute worst place to sit on an A319/320/321... The trays are in the armrests, seats B and E have the IFE screen in their armrests, and I don't find there's any more room than any other row. As a matter of fact, I find the immovable armrests particularly restrictive on these planes. I take seat 13D every time. Still near the front of the plane, has a power outlet and moveable armrests.

If you're dead set on buying preferred seating, take the emergency exit.