Thor, Surfer and Superman bring different strengths to the table.
- Thor (with hammer) I give the nod to in terms of sheer, overall power, not that the others are that far behind. He's also probably best at energy absorption (again, with hammer), which is extremely handy against a wide range of attacks.
- Surfer has the best overall versatility (jeez, the guy turned himself into snow!). I'm also inclined to give him the edge in durability and travel speed (again, the others not being that far behind).
- Superman, in addition to being physically the strongest and fastest in h2h speed, is the best puncher/brawler and definitely the most creative with his powers (SS and Thor should take note).
Personally, I consider any victory of one over the other circumstance determined.