1 15" or 2 12" alpine type r?

i have a kenwood KAC-9105D amp its puts out 900 watts rms at 2 ohms and >900 watts rms at 11 ohm... i was just wondering for this amp do you think one 15 or 2 12 alpine type rs would be better? because the amp would under power each sub by 50 watts if it was the 2 12s.. but the 15 i would have an extra 150 watts... so just let me know what you think...i listen to rap music and i like loud bass to the point where you can barely breathe.... so just let me know what you think.. and dont say upgrade amp because i only have enough money for new subs... thank you