I still think you are missing the main point here: "quite easily reached" != "optimal". The original question implied constraints of taking a 4 year undergrad degree and was asking for the degree which gave the best ROI($$$). it wasn't a question of undergrad vs starting a business or trade school or leaving highschool early to work in an oilfield ...
Which, again, I believe is asking the wrong question.
As for the "Doesn't matter, pick one" sentiment, I entirely disagree. I have seen too many of my friends spend a lot of time and money getting a degree that is worth very little, and pay for it for the rest of their lives. Yes it may be possible to achieve FI in almost any career, but it is a lot easier in some than in others.
I think you misinterpret what I'm saying there. I'm not saying pick one at random. I'm saying pick one that is right for you, because one degree does not make one more Mustachian than another degree. The answer to the question in the title of this thread is, IMO, "you can be equally Mustachian with any of them, there is no "Best" Mustachian Degree."
To answer OP's question, I would second the recommendations in this thread for a STEM (Science, Technology, Engineering, Math) degree. The work is generally challenging and satisfying, and on top of that it pays well.
I find it odd that you purposefully note aptitude and enjoyment in your post, then go on to recommend a STEM degree, which many are unsuited for.
That is why this is a silly question. What if you are terrible at math and science?
A question of: "how do I hit FI quickest, regardless of other factors" makes sense to ask, even if I think it's a damaging question life-wise.
A question of "what is the best mustachian undergrad degree" just makes no sense. It depends on
you, the individual.
And by promoting the idea that you need a certain degree, it totally undermines what Mustachianism is, IMO. Plenty of people give the complainypants excuse of not making enough money because they "chose the wrong major" - NO. Your major is irrelevant to you being Mustachian or not.
Could you have made more money quicker in another field if you were able and willing to do that field? Sure, and that's true of almost anyone. Can you not be Mustachian because you didn't get a STEM degree? Hell no.