hmmm.. I'd go for Sinister. He seemed to be well above and beyond present conventional technology, something that gives kang the edge when compared to.
Err how. Celestial powers pretty much dominate anything save reed tech. Baseline Sinister is also nothing to scoff at. Not even being dispersed to bits by Cyke's blast can kill him.
Well, Kang has that bad_ss time manipulation ability, he can send Mr. Sinister through the timestream at will, disperse him through different timelines or stuff. Without prep.
With prep he has already folded the universe into itself, created a multiversal artifact that can rewrite entire timelines and stopped a multiversal time eater, without using external artifacts of any sort, that's just his tech.