Silver Surfer vs. Thor

Yes prep

why would either need or use prep?.... unless Thor goes off and gets a bunch of mystical Asgardian weapons...... in which case SS is screwed

without prep i'd say it was 50/50

Silver Surfer cause he's "cosmic"

they have been stated in the marvel dictionary that mjolnir has about the same amount of power as SS's power cosmic.

They are pretty equal. Except that Surfer has that board that travels at light-speed which gives Surfer the edge in this battle.

Unless Thor has gotten some speed upgrade lately. I haven't read any of his comics in a while. With all the upgrades lately, I don't know.