So basically MVNO is a company that rents the towers from a major company that own them. Such examples are simple mobile, lycamobile, h2o, ultra mobile, net10 etc. There are a lot of mvno company's in USA. So the advantage of having directly the major company is that you will have priority on getting the signal when busy congestion hours. In terms of customer service that would be a hard to answer question as they are all different and alike same time. I have tested some of the mvno and some prepaid plans from major carriers and my experience was mostly the same, so for example lycamobile and tmobile share same network but of course the plans are different and advantages are different but coverage was mostly the same anywhere i would go. Well if you go for postpaid T-mobile everything changes as T-mobile will give you latest technologies like 5G and you will be priority on getting the quality signal in your area. I wanted to try Verizon to see if there is a big difference as it considered the luxury of wireless services. My experience was bad with verizon as customer service most of the time did not know what they are doing and after hours nothing was solved so their system is kind of bad. Service is good but it all depends on where you live, as some places you can get better service with ATT or T-mobile, so in terms of this there is no exact answer. T-mobile had the best customer service, fastest one and better solving issues. Att prepaid customer service department was no really knowledgeable on what to do. So in a short answer if you do not travel get a prepaid MVNO and enjoy the low price and benefits or get a prepaid major carrier company that will be a little more complicated to handle but still would be a good deal or if you travel get tmobile postpaid or google fi and if get verizon only if in your area you have only verizon service.