I use a variety of ways and voltages from 3v-18v. 3vdc+3vDC½wave) from 5vac, 4v ½wave from 5vac, 9vdc from 11-12vac. 12vdc from 15vac. 17v ½wave from 18vac
AC is rectified to uncapped DC with a bridge rectifier or sometimes "half wave DC" with a small diode or two in series on the circuit.
I'd run a 5v ac and 12v, 14v, or 18v accessory buses and step down voltage &/or convert to DC at each module as needed. That would be pretty universal.