Both are excellent engines. It is like comparing Ford vs Chevy. neither really has an advantage, but they do have faithful and loyal fans. I personally fly 3W and have loved my engines and the support I get from both Bobby at Cactus and Gehardt at Aircraft International. When I was in the market for a 150, I bought it based on the slight weight savings of the new one, and the conversations I had with Bobby and Gehardt. I had a hard time getting a hold of Dave at Desert Aircraft, but I know that he provides excellent service as well.

The only real advice I can give you is that no matter what engine you buy, go ahead and get the tuned cans instead fo the regular mufflers. If you fly IMAC, they are already becoming the standard. If you just fly for sport, your club with appreciate the fact that you are more quiet and - as a bonus - you get about 200-300 RPMS over the regular mufflers. Again, my preference is the 3W cans because they have a cross-over tube to make the mid-range smoother and less "pipey", but DA sells a really nice set of cans as well.