Ideally your ground should be 0 V everywhere, so a voltage drop due to any impedance is out.
Olin notes that connecting grounds with inductors means they won't be connected at high frequencies, so they aren't grounds anymore. That's correct. But if you completely isolate your digital and analog part for high frequencies you won't need a ground return path for them either. This makes only sense if you block the high frequency noise in all other connections. Power supplies and signals. I've used Murata BLM noise suppressors for this; a BLM18PG221SN1 has a DC resistance of 100 mΩ maximum, and an impedance of 220 Ω at 100 MHz.
Combined with a capacitor you get a second order filter which will deal with that microcontroller noise. The low resistance means a minimum voltage drop in supply voltages.
If you can keep HF noise away from the analog part you can couple both grounds directly, but at 1 point.
When I worked with Philips Audio wired ferrite beads were sometimes used to connect digital and analog ground:
DC resistance is in the milliohm range, but like Olin says they will offset ground for HF
if you allow it to pass to the analog side.