I never used Sust as I never quite understood the fascination with it. Other than that, to me cyp, enanthate, and even prop are much more similar than many would expect. I'm prone to think the differences in Sust are a little exaggerated as well. Thing is, so many people keep talking about the differences in different forms of test yet if one looks at charts of testosterone levels over a period of several days, it seems odd that there used to be so many heated arguments over the matter. (There also used to be this common mistaken belief that it takes several days or even weeks for levels of testosterone in the body to spike after an injection of anything but suspension, yet blood tests show that's simply not true.)
As was alluded to by others, I simply can't see much of a reason for using anything but enanthate or cyp. (extremely similar) for a first cycle if it's available and the newbie wants test. Once price, effectiveness, and so forth are factored in, there's a reason it's the standby.