Niether Thor nor Thanos are as mobile and fast as Superman. Not That I think Surfer Loses, but he sure as hell doesn't take an over whelming majority. Superman is as powerful as the surfer. just less versatile with the very weaknesses that just happen to be surfer's specialty. Take Superman's weaknesses away and Surfer would be up shit creek.
Superman would lose in an overwhelming majority though. His weaknesses make him so underpowered that normal humans like Batman can wail on him when he's exposed to them. The Surfer can literally make these weaknesses from thin air, and is at least as strong as Supes to begin with, so there's really no way he could lose here.
Take away Superman's weaknesses and the Surfer can still go back in time and destroy him before his birth, use the PC to increase his strength and speed to levels far beyond those of Kal El, etc. Even without the weaknesses Surfer takes a victory, his options are just more limited.