I am both a founder and an MBA grad, so perhaps I can add a little value to the conversation. Bill had a good point that it depends on what you want out of it. I would add that not all MBAs are created equally, so it is all the more important to know what you want.
Some people just want 3 letters after their name. In that case, do the cheapest/easiest MBA you can find. There are lots of online courses/schools that will confer those letters on you.
I will assume, for the pursposes of this response, that you are looking at doing an MBA because you feel that it will make you a better entrepreneur or business proprietor. If so, then I think the answer is it depends.
There are two aspects that I think an MBA could help you with. The first is a strong foundation in business. Many people are very strong in a couple of business disciplines (like Marketing or Strategy) but not particularly strong in others (perhaps Operations or Finance). An MBA will give you the foundation that is required to become knowledgable in these disciplines. This is important, because as an entrepreneur, you NEED to be functional in ALL disciplines. Could you pick up these things as you go? Sure...but you will make mistakes as you go, and certain mistakes might be fatal, and you might have avoided them had you been more knowledgable.
The other thing that might be of interest to you is the network of alumni that a particular school has. Stanford has an incredible list of alumni that I believe is really engaged in the school. There are many other schools that are similar.
What an MBA will not teach you is EVERYTHING else that is required to make a go of a startup. Specifically, I would suggest the following things (this is not exhaustive) that are not taught: tenacity, real-world problem solving, getting into the weeds, staying above the clouds, gumption, real-world networking, being a generalist (when needed), being a specialist (when needed), managing people, hiring people, firing people, raising money, building relationships, compromise, being humble, defining what you really want, ...
One other point that is perhaps important to consider too. My experience when it comes to MBAs (especially at the elite schools) is that they are attended by A-type personalities. Everyones dream is to be the CEO of the largest company in the universe. (I am generalizing...but I've only got broad brushes right now.)
I would suggest that being the CEO of a small highly profitable company where you don't have debt or investors would be a much preferable option. You aren't beholden to anyone...you would be your own man.
Regardless, an MBA might help you on your way.