A new PI or the brilliant current PI
The criteria I think are important here:

Growing your social capital. In academia, the size and diversity of your professional network is a huge determinant of your success (think co-authors on grant applications and papers, colleagues on editorial teams, and advisors for your PhD students as well as diversity of ideas, methods, and philosophies, and, yes, employment opportunities). It sounds like you've already built a great network where you are, so a good thing to do might be to go an build another one somewhere else, obviously without abandoning your current contacts and relationships.
Slightly contradicting my first point, what kind of professor do you see yourself in a couple of decades? Some people love interdisciplinary research projects, leadership positions in international networks and consortia, and variety and mobility in general. Others do their best work spending years or decades looking into one or two big questions, surrounded by good PhD students and loyal colleagues. I.e., it's also a personality question.
How would the move affect your life outside work? Will you have to sell your house, move to another part of the country you've never lived in (or to another country that speaks another language), and rebuild your life? Do you have care responsibilities for your parents or children? Can your finances handle it? All this is a huge thing that often gets overlooked in the pursuit of some imaginary professional success. Over the decades, I've seen junior colleagues move to the UK from the other side of the globe just to pack up and go somewhere else 2 years later, without much to show for it.