Hi Bill,
It depends on what you are looking for in a software for which is better. These two programs are quite similar.
Power2Go is mostly for burning data discs, music discs. The features for video disc burning is ok, but limited compared to others (PowerProducer, PDR). However you can do some minor of trimming of video in the program.
MakeDisc is Media Center compliant and is more of a step process application for making discs. It is more graphical, but overall you have less control over the disc making process (compared to Power2Go).
For more information, though I am guessing you have read:
Power2Go:
http://www.cyberlink.com/products/power2go/overview_en_US.html
MakeDisc 3:
http://www.cyberlink.com/products/makedisc/overview_en_US.html