There's a few battles between Thor and the Surfer, but it's general consensus that, as of now, the Surfer is more powerful.  
 
Iron Man is no match for the Surfer unless he can create a device or suit to siphon the Surfer's Power Cosmic, which he is most likely capable of doing since the Black Panther has done it. 

in general, Silver surfer is one of the most powerful heroes in marvel, but he is very vulnerable to have the power cosmic stolen from him. doctor doom, red hulk and skaar have all tried to steal the power cosmic.

who can beat silver sufer ,i think HULK can beat every marvel characters(of crouse not every time)

Surfer was not nearly as powerful in the movies as he is in the comics. He could simply turn Iron Man's armor into flower petals, then a long fall down and its over.

" @jloneblackheart: iron man is one of the most powerful guy in marvel not such easy  to defeat,and SS have been beat by human tech in FF2 FILM. "

" who can beat silver sufer ,i think HULK can beat every marvel characters(of crouse not every time) "

" a stupid guy said SS can beat GR easily ,what a idiot. "

"who can beat silver sufer ,i think HULK can beat every marvel characters(of crouse not every time) "

"@difficlus: i still think SILVER SURFER can't beat GHOST RIDER easily (and i still think that guy is idiot),GHOST RIDER is really powerful(if you read lot of ghost rider you will know) anyway ,non canon doesn't mead it won't happen ,beacuse anything is possible in marvel. "

The only hope Ghost Rider has of winning is the penance stare, which should work on the Surfer (who is responsible for the deaths of billions), but then again he's been down that road before and has come to accept what he has done. 

@Fire-brand:
you're the childish one

"@chris thompson: no, you said that because you like silver surfer more, it's not ture. "

" @chris thompson: i read your list ,hulk is top 4 ,ss is top 3 ,what about venom vs ss? "

" @ka385385 said:

" @jloneblackheart: iron man is one of the most powerful guy in marvel not such easy  to defeat,and SS have been beat by human tech in FF2 FILM. "

I don't really know if I would call the Fantastic Four films canon. I mean, wasn't galactus just a giant space tornado in that movie? "

 VS. PROF. X: Yeah, you guessed it, between the Surfer’s incomprehensible speed and indomitable will, Prof. X may give the Surfer a run for his money in chess, but not in combat.

VS. SPAWN: The Surfer’s faced down Mephisto, Marvel’s version of Satan, so a Satan-flunkie like Spawn ain’t gonna do much that the Surfer hasn’t overcome before.

VS. DR. STRANGE: Dr. Strange is a human conduit of magic with human frailties, while the Surfer can stand at the center of a super-nova without breaking a sweat. It might take a couple of hours, but Strange would burn himself out trying to dent the Surfer.

VS. FLASH: Sorry, the SUrfer is faster than the Flash, with the power of the universe at his command. Once you take away his speed, Wally is just a guy. G’night, Wally.

VS. WONDER WOMAN: Diana may be a better fight, but the Surfer is faster, tougher and more powerful. Ten bucks says Wonder Woman’s bracelets aren’t up to deflecting the power cosmic.

VS. SUPERMAN: While Supes might land a couple of blows as the Surfer is trying to talk to him, our bald buddy Norrin could either hammer Supes into submission with the power cosmic or suck all the solar energy out of him with his energy manipulation powers.

VS. THOR: Surfer’s power cosmic is fairly evenly matched with Mjolnir (whose magical properies aren’t affected by the universe’s laws of physics), which would absorb/deflect Surfer’s power for a while. While Surfer couldn’t do much physical damage to Thor, Thor would hammer the Surfer unconscious ... if he could hit’em. And even though Mjolnir could block Surfer’s powerful blasts, some would eventually land. As the battle progressed, more and more of the Surfer’s blows would connect until one super-blast of the power cosmic would put the Odinson down for the count. And the worst part? The Surfer, one of the most noble spirits in the universe, would search the rubble after the fight, grab Mjolnir and head off to Disneyworld.

 A crazy bloodlusted Surfer not holding back would kill your regular Spawn with speed, Spawn has never fought anyone as fast as Surfer.  Plus Surfer can always pull off insane moves like dump people at the end of the universe or transmute them into a bunch of flowers or he has done other tricks like attacking people's spiritual form. Spawn has not seen even half the crazy stuff Surfer has done over the years.
 
 Surfer on an normal day would trash Hulk and Superman both at the same time, 
Spawn on any normal day is not a guaranteed bet. A lot of people can take Spawn with a bit of luck
 The reason I don't buy into the Spawn hype is I think Spawn's power base doesn't really exist, his power goes up and down like a flag pole, Spawn has had people feed off him, had his nerco meter drained or Spawn has been made powerless by artifacts from heaven. At a normal levels I think Spawn falls to Surfer,  he's got some low showings like he can be the type of magical dude who has trouble with punks with guns or gorillas enhanced with cybernetic parts

but it all depends who writes it, if McDuffie wrote I'm sure Surfer would randomly fall off his surfboard and get killed by an armlock. Or if Spawn is amped up to some immortal God/Devil level with infinite levels of  necroplasm pouring out of his eyes I guess he wins by default
 
btw the above post   
Surfer
VS PROF X
 VS. SPAWN: 
VS SUPERMAN
.VS. DR. STRANGE
 
...its not mine, it comes from the old Wizard magazine
I just happen to agree with their post