Any autopilot that integrates into the MFD should be able to stand alone. Or the other side of that, is that you probably should have two MFD which will function with the auto pilot, radar, sounder etc...if you should loose one. For example my current boat has Garmin displaces which are not networked, but either one will do all I need to be done--Radar, depth, course/speed, chart plotter.
If I buy another slightly larger boat, with an autopilot, and a single MDF, I will buy a second MDF, smaller, which will do all functions. Although redundancy is one goal, the other is to have adequate screen size for each of the 3 crucial displays.
Even if the pilot does not stand alone, most can be configured with a separate compass--fluxgate, gyro, or GPS, which will work--and make it independent. You are going to get more out of the pilot if it integrates with the MFD.
I think that today all of the major brand autopilots are good, (RayMarine, Garmin, Simrad (lowrance, B & G.) Furuno, and there are a few independent--like com Nav, Sitex, Hummingbird, etc. The only one I would not consider is "AutoNav"--and only because I had such a miserable experience and felt that they were dishonest--failed to stand behind product.