I will give my opinion, but understand I have not used any of those choices, but is based on thinking that went into me designing and building my own machine.
24V is not sufficient for any Nema23 steppers (Should be 48V or higher), so that eliminates several of those (I.e. Blackfoot controller is 24V). . Millwright attaches 2 steppers to a single driver, that is poor design as well. Stiffness and speed are the primary characteristics I looked for (speed = proper chip loads = cut quality, longer bit life), so none of the machines with 3D printed or plastic structure (longmill, nextwave) made my cut.
The best advice I can give is don’t decide based on how much money you have burning a hole in your pocket, decide based on what you want to be able to do, including size and materials. For me, things like being able to work ends and edges of boards and handling full sheets of ply was important, I’m sure you have developed your own list (if not, you are not ready to buy).
Tubular latex pressure vessel configuration engineer