I'll tell you working on a master's was really invigorating for me. Some of the mental flexibility or plasticity returned that I hadn't felt since I got established in my work. I'd recommend it to anyone, though like everything else it's so much better when you can meet in person.

The PhD on the other hand is more like a regular job. That's not to say it's a bad job but it's more about getting things done than just taking time to grow in your knowledge.