Arduino is primarily a learning and hobby product, not a commercial product.
I use both MPLABX with various PICs, and Arduino, both for hobby projects. The Arduino environment I find very useful for the wide range of libraries available, for example I would not know where to start to get a PIC connected to WiFi, but using the Arduino environment and ESP8266 boards and libraries it's easy.
They are different tools for different jobs, your question seems to suggest that you want a sales pitch, I don't think you are going to get one on a support forum run by hobiests. In any case, only you know your applications and requirements, you have to decide which products meet your needs, no one can do that for you.