This thread sure has gotten interesting...
Neither Sentry nor Surfer are anywhere near as hyper-powerful as some would like them to be. Neither of them are lighting up the other with a billion suns worth of power while the other one laughs it off and battles headless and in pieces while intangible at 1000x light speed.
If and when they fight on panel (eventually we all know it's going to happen) I'm certain that they will definitely hurt each other if they go physical. Neither one is going to have an easy time with another.
Meanwhile, Sentry is going to have more lows than Surfer as for one, he's an Earth hero. A majority of Surfer's lowest showings have come from his time on Earth. It's a given that on Earth these guys are usually toned down somewhat.
Going by Surfers/Sentry's showings vs Hulk, well, Hulk has a variable strength rate whether when angry. How does one measure exactly how angry/pissed Hulk is? The only thing we know is that Sentry fought what is currently the most powerful version of the real Hulk in a head 2 head battle. He doesn't have the ability to drain Hulk... then again, Surfer doesn't have the ability to calm Hulk either. We don't know if draining would have been viable against WWH. We do know that Sentry's darker half (void) destroyed standard Hulk effortlessly though. While Surfer has beaten Terrax without too much hassle, he's never owned Terrax with the casual ease that Sentry has.
In short, while this is Surfers fight IMO, short of a bfr, Surfers going to work for it.