Actually, Sentry has the potential to "fiddle" with matter. Power-wise and potential-wise, Sentry has the win. In practice, the Surfer at this point. The Sentry's power is rumored to be (by the creator of the serum) unlimited, and it shows with the planet cracking, soul feeding Void, which is always the underdog of power. In fact, Sentry's the only one capable of taking care of the Void. Easily, I might add. Speed wise, we haven't really seen Sentry go much further than the sun in a few seconds, which means he's at least around ten times the speed of light, since it takes light around ten minutes to get to us, and chances are, he's probably navigated space alone and such. He was capable of taking care of the Inhumans rather easily, and was capable of fighting the Hulk hand to hand with little difficulty on a physical level, which Surfer has yet to meet up to on either.
It's just that the Surfer has gone around using his powers more with practice, and doesn't have any fears about what the upper levels of his powers might do. Where the Sentry's powers could literally go on forever, but forever trigger the Void, so he usually keeps his power lower.
So chances are, if the Sentry didn't really mind the Void making some sort of debut, he could stomp the Surfer, and fend off Galactus. And, if the rumor is correct, he can overcome Galactus. He's literally rumored to do anything he wants, a power infinite of sorts. He cured a mental disease with little effort, after all. However, chances are, he'd have to merge his Void and Sentry selves for that.
Either way, it could almost be said that a Million Exploding Suns is nothing more than a match flame to his true power, if he ever revealed it.
