I have 3 powermeters - an old Powertap Pro+ hub, a Power2Max in a Rotor 3D crank, and a 3rd generation Stages (Left side only). They have all been very reliable, they give the same numbers
Do you have a frictionless drivetrain?
My PT G3 hub is about 4 watts off from my Quarq Elsa and Riken with a static torque test, which is expected since it is upstream from the weight on the pedals. As a recreational level cyclist, these PMs have been great for me, but I know that most of the serious guys that frequent Wattage seem to generally trust SRM more. If I were to go with the OP's question and money was no object than I would no doubt go with the SRM Orgin.