Necro's can run any Rt build not focused on spawning just as well as a Rt primary and have even more energy to fuel them.
Rt's have some of the coolest armours and animations though
A good way to choose is to compare a Rt minion bomber with a necro MM and choose which you prefer i guess. I personally prefer Rt for hybrid builds that have access to utility from other professions such as expel hexes or various monk hex removals.