The formula for the loudest design is no secret.
The driver that has the most: surface area, power handling, efficiency, excursion.
The box that is: the biggest, and most-efficient design (horn > ported > sealed).
All else being equal: the system driven with the most wattage will win.
The biggest driver = advantage
The highest wattage driver = advantage
The highest efficiency driver = advantage
The highest excursion driver = advantage
The biggest box = advantage
The most efficient box = advantage
Driven with the most watts = advantage
The one with the most accumulative advantages will win, more or less...
That said, those are some wildly varying wattages, box sizes, and box types you have there. But the above still holds true.
The characteristics of different drivers and box types are well-known at this point, i.e. databass and other such.
As for the testing procedure itself:
Keep in mind that most 1/8 or 1/4" mic max-out at around 130db, so you'll probably have to test at 10m to avoid mic clipping/mic distortion. In fact most start distorting at around 120db and up.
If measuring in a room, the low end will have some room-gain, and there will be room-nulls based on positioning (distance from driver to wall(s), driver to mic, wall(s) to mic. etc). Measuring outside well-away from walls is best, with the mic placed on the groundplane (i.e. databass style)
I would recommend at least two sets of comparisons: one where they are all driven with the same wattage (the highest wattage of the weakest box design); and another with no holds barred.
Just keep in mind that the chance of your drivers surviving these maximum tests are low.
I mean if anything is gonna blow, it's gonna be during a maximum stress test; which is pretty much what this will be.
But if you have the spare cash on hand to replace whatever dies, then go for it I guess.
It's always fun to spend other peoples money, just ask any wife/girlfriend.
(and on that note: your taxes and child support is now overdue, so pay up or go to jail/fined/repo'ed/frozen-bank/revoked-license/all-the-above.