No healthy monitor will be "tame". They can learn to tolerate your presence, and will readily approach you for food, but if you are looking for something you can hold on a regular basis, Varanids should be crossed off your list. They will spend a good portion of their time out of sight when you're around, (Argus and Ackies less so than Savs) and will not be thrilled if you grab them. Interaction should be on their terms, not yours. Monitors do not deal with stress well, so they will remain primarily a display animal apart from interaction during feeding time. Out of those three, an ackie is your best bet. There are not a lot of people capable of caring for an Argus, and only slightly more capable of caring for a Sav. Even monitors as small as Ackies will eat more food than you could imagine, the larger ones are bottomless pits.