The SKR Pro is supposed to be somewhat “future proof” although Biqu seems to be stopping production of them. Some users have also had issues with the end stops, but that’s manageable.
It is one of the supported boards for the MPCNC and LowRider machines, so getting it running and starting you learning is relatively easier.
The TMC2209 drivers are nice to haves. The quiet aspect isn’t a big deal, but they’re solidly capable drivers that can deliver current.
12V vs. 24V is a whole kettle of worms by itself. These machines are all designed to work fine with a 12V supply. Give or take 6A for current requirement should be OK. I might go a bit higher for headroom, but that should handle almost all usage cases, except possibly adding a diode laser, which might require that much or more just for itself. Most diode lasers seem to run on 12V so if you are planning to add one, you can save a bit of trouble if you get a bigger power supply (12-15A? Depends…) off the top.
24V gets you higher speed limits, but does not seem to deliver any additional motive power. (From my experiments.) While working, the machine should stay within the limits that 12V allows. Also, 24V accessories like fans are harder to find and often more expensive. You also need the same current from a 24V supply.