No weapons for any, just using their natural talents here!

Khan of the reboot, Spock of the classic series here!

I think Spock of the classic series goes down first, but I think this is a close fight.

I think even classic Khan and Spock make it a good fight...but I still give Slade's healing the edge, and comic book characters with experience fighting more powerful characters the edge.

In general, I think Spock and even classic Khan are peers in strength to Slade and Cap...but the're not as fast, agile, or as good at fighting.

Transplanted, however, I think Khan would end up being very much like Slade as a villain....

Spock though was shown and said to be a Vulcan master of martial arts, and Khan had a healing factor also, so could still win this!
Spock would be maybe 3-5 X peak human, Khan about 10X

but I don't think Spock is 3-5X Peak Human. I think he's maybe 3-4 times a human of his height and build. Very likely above peak human strength, but not above.

Khan, classically, stated he had 5X Kirk's strength...Kirk was not peak human...Kirk was in VERY good shape, and if he fought Batman it might be close, but Cap is, IMO, clearly stronger and more durable than Batman (Batman has other advantages though). So, IMO Khan classically may have been in the peak human, 1 ton, or 2 ton range, likely toward the lower end. The more recent version seemed more impressive, but how much of that was budgetary or special effects vs. real difference...a 1-2 tonner could do whatever he was doing.

So, I'd say Khan is somewhere between peak human and 2X peak human, as is Spock, but Spock is on the lower end of that range, and Khan a bit higher....but a lot of ambiguity.

They both MIGHT be slightly stronger than Slade or Cap, but not by a huge margin. They're both skilled too, but Cap and Slade are more skilled, and more used to fighting characters that are stronger...

On paper Khan and Spock are a good matchup, but ask yourself, do you honestly see Spock or Khan defeating the level of characters that Captain America and Deathstroke have faced down? Cap and Slade routinely take on characters waaaaaay beyond their weight class and sometimes TEAMS of them and, not only do they come out on top but they make them look like chumps more often than not. The TREK universe simply does not have characters of a superhuman caliber for Spock of Khan to face on a regular basis. In the Trek universe, Khan would be considered a Super Human but by DCU or MU standards, he's pretty low level. Heck even DATA of TNG would be considered low end Meta by those standards and he is probably at the top of the TREK universe scale that we have seen.

Experience fighting much higher end superhumans makes a HUGE difference in my book.

True, but Spock still very skilled, and probably equal to steve physically, and Khan is enhanced like slade isalso!

True, biut would seem to be a good matchup here, and the team 2 had better be on their A game here!
What if spock gets cap in that vulvan neck poinch though?

Well it managed to put Logan down!