so I have used both and my results are:
Thermal Transfer - I have come to realize that paste has always worked better for my applications . Pads are not the worst thing in the world but I advise too stick too paste .
Also keep in mind that Microscopic groves etc are in the CPU , paste fills those better then a pad .
Theirs also a few videos online ( one from jayz2cents ) etc proving that the pads dont work aswell as paste .