I prefer to use RT. I have seen quite a few RT's that pass bend test but won't pass RT. You can get a much better feel for the quality of joint prep and level of attention to detail a welder might use. Also, at least in my area, there is competition for welding jobs. I, personally, feel RT is harder to pass than bend test.
The only problem that I have is per ASME, RT for WPQ's is not allowed for FCAW and we run a lot of FCAW.