Hm, I'm just wondering how either team could take out Carnage or Sandman

I think that Doc Oc. with prep will defeat Carnage.
 
Sinister Six ftw. Sandman almost solo.

Carnage, Demogoblin, Charrion, Doppleganger, and Shreik...   

Kraven, Doc Ock, Mysterio, Electro, Sandman, and The Vulture.  
 
 
I'd give it to the Sinister Six in a pretty large majority.  With prep, Kraven and Mysterio will be pretty heavy threats to the overall team(Kraven has managed to trap Venom in a wall of flames, Mysterio can distract the foes as well as incapacitate them), and current Electro is a powerhouse who could have a field day with all of the electronics in the building.  Vulture is a mere distraction, and Doc Oc could likely beat Demogoblin (he's defeated Hobby). Now throw in Sandman, and I'd say the Sinister Six take a massive majority.  Sure, Carrion is a massive threat if he touches someone, and Shriek can dish out some good damage (although she was completely unable to tag Spider-Man and was then one-shotted), but in the end it simply isn't enough to counter the S6's many advantages.  Plus, the Carnage family hasn't done a thing with prep other than attempt to go on a killing spree, which would likely be their master plan here--- "kill the opposition".
   

No one in the Carnage family can really do anything with prep. Doctor Octopus and Mysterio on the other hand are excellent with prep.
 
@Dracade102:
When you say standard equipment what do you mean? Mysterio uses a large variety of equipment so specifics would be helpful. Doctor Octopus, Vulture, and Kraven also have multiple versions, so specifying there would also be helpful. Power levels are also important, as current Sandman and current Electro both have increased in power quite a bit. (Current Vulture is also stronger, but that's more of a version problem)

" @Bolzar:
Current Vulture isn't the same character, though, and has never been a part of the Sinister Six roster.  So I think it's fair to assume this is Toomes. "

"No one in the Carnage family can really do anything with prep. Doctor Octopus and Mysterio on the other hand are excellent with prep.
 
@Dracade102: When you say standard equipment what do you mean? Mysterio uses a large variety of equipment so specifics would be helpful. Doctor Octopus, Vulture, and Kraven also have multiple versions, so specifying there would also be helpful. Power levels are also important, as current Sandman and current Electro both have increased in power quite a bit. (Current Vulture is also stronger, but that's more of a version problem) "

I will still choose the Sinister Six, although it is a much tougher fight. Carnage is a huge threat, but his allies are not nearly as useful. With a week of prep, Mysterio, Doctor Octopus, and Kraven will go to town, creating a no doubt insane set up for their opponents. Add in near powerhouses like Electro and Sandman and the S6 should take a solid majority.