I always noticed that the Soundcraft had better internal wiring/ construction than the Tac. The topology of the Tac is also denser, by twice, and the quality of the boards is not as good as the Soundcraft. It tends to get lifted traces when re-capping. The simplicity of the Soundcraft trumps any AMEK EQ or extra function of the TAC, IMHO.
MCI? If you want the best sound of the three, a HUGE maintenance headache, and 200% higher electricity costs, then go for it.
Oh, and if it has the plasma bargraph meters, even bigger PITA.
Mike