You opened up a big bag of generalizations without knowing it, py generically just referring to "PVC" membranes.
Is any white membrane a PVC membrane?
Do most white membranes contain a portion of PVC in it's formulation?
The answers are that each and every unique manufacturer formulate their own recipe for their white thermoplastic membrane roof products.
Some, such as TPO membranes, while offering a lower initial price, have been shown to fail rather regularly, in about 10-12 years time, regardless of the quality of the installation.
Others, such as pre-fabricated systems, like Duro-Last, can perform quite well, but is totally dependant on the quality conscientiousness of the installation crew for final aesthetic appearances, due to the factory folded creases which must be streched out properly when laying it out.
Others, while not being factory fabricated and coming only in roll goods, now depend on the quality of the installer doing the seam welding or the knowledge of the operator running the automatic robotic welder running the saeams.
Once you have a quality contractor familiar with any of those systems and see their actual work, then you will know if that roof membrane will be a good fit for you.
What aspects of the roofing material are the most important to you?