What is the best chemical compound for dissolving a human body?

I'm writing a short story about a serial killer, and this would be helpful info. I know Dahmer used hydrochloric acid, and John George Haigh used sulfuric. Mexican cartels are fond of lye, and many others (including the "death squads" of many despotic regimes) have used quicklime. I just would like to know which of this does the job most thoroughly, and in the shortest amount of time. If there's one that works better than any of these, what would it be. Thanks.