I feel the that we the fans do the franchise a disservice when a majority of us all clamor that TWOK is the best movie in the franchise and the other 10 films don't hold a candle to it. The same thing can be said about Khan as a villain. If the bar is set by what Khan did then the villains from First Contact, Nemesis and XI all surpass Khan as I illustrated. General Chang from Undiscovered Country also surpasses Khan by his own actions and merits. I didn't include him in my character comparison of Khan because his actions and motives don't overlap with Khan's own like the villians of ST VIII, X and XI. IMO ST VI is the best of the TOS films because of it's themes, story and full use of all the cast. While TWOK is just Kirk, Saavik and Spock in a minor capacity. All the other crew were pushed into the back.
Star Trek is more than TWOK. While it is a good movie I don't think it should be the Torchbearer for the entire franchise. For instance Gul Dukat is a great villain no one sings the praises of. Granted we were given 7 seasons to peel back the onion of his character. To see him function as an antagonist, rise with the Dominion, fall in to madness and later resurface as a acolyte to the Pah Wraiths. I've outlined everything Khan did, except what we were told about him in the Eugenics Wars. With that, it is still only exposition of why we are told Khan is so threatening we never actually see the fearsome warrior and calculating genius we are constantly told he is. By that standard Dr. Bashir could be a comparable. He was genetically altered, and he displays genius, enhanced abilities, ambition and was shown working out how to tactically outsmart the Dominion and secure a Federation victory but to no avail. Showing and telling have a different effect in their delivery. If JJ really is having Benedict Cumberbatch portray Khan I welcome it, just like I welcome JJ's reimagining of the Klingons.