Thor all day long as pertains combat related feats...
Surfer has (naturally IMHO) shown greater energy manipulation powers though such as when he controlled the Big Crunch energies...
As pertains overall power level, I believe they should be in the same tier (which they are) but Thor's might is more combat oriented than the Surfers.
As pertains combat related feats (strength, durability, raw energy output) I wont say Thor grossly outclass's Surfer, but he definitely exceeds him...
Withstanding direct attacks from the Celestials while still being durable enough to continue fighting, lifting a portion of the world serpents mass, and his accomplishments with the God Blast and Anti-Force all exceed feats performed by the Surfer in each of those catagories...
^^
Feats like that is why I consider the overall power level of the two characters to be in the same neighborhood; Thor has no energy manipulating feat anywhere close to that...but by the same token, Surfer has never ever proven to be capable of injuring a Celestial under his own power (such as Thor did to Exitar with the GB).