Powering microcontroller by bypassing ldo regulator
I know the answer is subjective.
I use this whenever there is a need to switch between two supplies with at least 1 V difference automatically.  Here, assuming VIN_EXT is less than 5 V, the circuit will draw power from PC whenever USB power is available, else from VIN_EXT automatically.







simulate this circuit &ndash; Schematic created using CircuitLab

Major advantage here is that, drop across the FET will be just a few 10s of mV at max compared to diode drop of about 300 or 400 mV