Courtesy of Justin Fore at Fore Innovations LLC:
This generally depends on the nature of upgrades in the entire vehicle. While all three fuel system types are capable of supplying fuel for significant power, return type is universally accepted as the most flexible and easy to tune for max power, driveability, and consistency. If you are making relatively small upgrades to your engine (i.e. supercharger with low boost) then it usually makes more sense to maintain the fuel system type and upgrade the capacity within the constraints of your OEM fuel system type. High power builds (forged motor + big boost and/or nitrous) should be converted to a return type conversion for maximum performance, enjoyment, and protection of your investment.