Selecting a power supply is somewhat anticlimatic in comparision to some of the other accessories. It is a matter of getting a supply that is big enough to support your accessories
Power supply calculator
https://www.bequiet.com/en/psucalculator
Power supply calculator
https://www.coolermaster.com/power-supply-calculator/
Power supply calculator
I choose a modular power supply so I can connect only the cables that I need and specifically the Dark Power Pro as the cables were slightly longer than other bequiet power solutions.