Which subs would be best for this amp?

i have an alpine mrp-m500 currently i have a kicker cvr 12 dual 4 ohm, an alpine type r 10 dual 2 ohm, and a memphis pr 12 dual 4 ohm, out of these 3 what would be the loudest? i've thought about the dual 4 ohm type r so i could wire it down to 2 ohm and get 500 watts, but i've also considered 2 memphis pr 12 single voice coils so i could wire them down to 2 ohm. thanks for your input.