Which subwoofer should I buy?

I would like to buy the Yamaha yst sw 310 or the Polk audio psw110. Which one do you think perfroms the best? Right now I have Microlab Solo6c 2.0 speakers and I would like a subwoofer to compliment them. The Microlab is 100 w. I have a room that is very oddly shaped, with a lot of corners and so on. The roof is not flat but it is like a traingle (i don't know how you call it). But the room is approximately 8-9 meters x 5 meters. So which subwoofer should I get?