It really depends on personal preference. I myself have a sader that does T3 effortlessly and that's with no set items aside from aughild's 2piece + RRoG. I also have mage and barb friends that do the same thing with equivalent gear. All classes can do all Torments, some just need more gear than others/require certain builds to progress
i currently have
70 barb, 70 sader, 60 wiz, 65 monk,60 WD
i enjoy playing all of them accept WD but i cannot decide which i want to properly gear...help.