Tokyo Marui AWS L96 (BB weight)

Tokyo Marui AWS L96

The part list I bought is: 6.01 Precision Barrel, Cylinder, Cylinder Screw, Cylinder Head, 7mm Spring Guide, 500 FPS Spring, High Pressure Piston, Trigger Sear, Piston Sear, Spring Guide Stopper, and Maple Leaf 60 degree Rubber.

Note: I having my local airsoft store upgrading my gun and sighting/zero-ing it in for me.

Because I have a 500 FPS spring with .20s, what's the recommended bb weight and brand I should use?

I am thinking .32 and haven't shot with those as I only have .25. Although from all the forums I'm seeing, I see .36 being used a lot. Please indicate the pros and cons of using a .32 BB (best brand you can think of when listing pros and cons) and with my gun should I be pushing higher?