Did you notice that everyone is telling you to port it? By chance? If you want the system to get loud, port the setup. The W1's don't have a great sensitivity so comparing the 3 12's to two fifteens, where both are ported, you should come out louder with the same given input power with the pair of 15's. Only if you port it and port it right. If you want to compare sealed to sealed, why not just go with the cheapest one, they'll all **** in comparison to the ported option. The only reason you are asking ANYTHING about a pair of 15's is because you are a basshead. Feed the hunger and go with a ported enclosure. The two fifteens vs. the three twelves will be very close in output on medium power like you are talking about. Go with the cheapest one FTW.