150 sounds better for your weight and height. i am also 5'8.5" and weigh 135lbs. I have the pickle in 150 and it is great. I had the 147 before, but the topsheet cracked after 3 days, so i got the 150 as a replacement from sport chalet (they will take ANY board that they carry and replace it for you, even if you didnt buy it from there, pretty awesome). the 147 was more fun to play around on in the park, but the 150 feels stabler and doesnt stick like the 147 for me.