I have just based my order of preference on -
Ease of setup (wiring etc)
Ease of tuning of ignition and fuel maps
Amount of tuning options for fuel and ignition maps
Adaptability to a range of physical inputs including coolant temp, air temp, pressure change, knock sensing and lots more as conditions change. This can be done on individual cylinder basis on better ECU's.
Ability to run sequential injection.

There are lots more things that make my subjective ranking appear in the order i have given. These are just some of the things that immediately spring to mind.

Agreed my ranking is based on a personal preference. But it is based on facts from actual use, not just an excuse for argument or point scoring.

I currently own an Autronic SMC "auto tune", Haltech E6A, Motec M4 version 4.5.

I have owned two Microtechs. Both were troublesome. I have only worked on Wolf 3D's but find them good quality and easy to use.

Rather than Microtech (but in the same price range and much better value for money) is the Hawk system. It is sold by EFI hardware. This is a good quality cheapy that really works and has plenty of functions..

The ability to run peripheral systems is only a very small (but useful ) part of the functions of the ECU.

My 2 cents worth