Phasor xs is a brand name, not a method.
Your question would then be Phased array Ultrasonics vs. Radiography.
UT in general will have a higher probability of finding planar flaws. (cracks, lack of fusion)
RT will do a better job of finding volumous flaws. (porosity, slag)
Most codes require Automation for UT code exams.
RT does not.
The closest equivelent to AUT/PAUT is Computed Radiography.
The same percentages and flaw types apply as for basic UT/RT with the exception of the overall POD increasing dramatically.
The codes, standards, and specs that apply to your project should take precedence over opinion.
Regards,
Gerald