The reason I would use a relay is because when I worked in industry that was the standard method for a reason and I liked it, same thing with PLC's
It was found that if a fault developed it was cheaper, easier, quicker, to replace a small plugin relay than a VFD, PLC, or the device controlling it.
Galvanic isolation with a set of "volt free" contacts would always be my solution, there can be some undesirable and unforseen results by connecting supposed "earths" together.