I'd say they're both pretty close. You may get better responses if you posted this in the correct forum.
My $.02 is that fusion was faster when I tested both out, but I suspect that parallels may have caught up. I know in fusion you can utilize both cpus and parallels you cannot (at least couldn't, I don't know if that changed) This alone increases the performance of fusion.
Regardless, I think the speed difference is small at this point and go with the product you like the best. They both have good and bad points