All depends on what you have and what you want I suppose.
For me I want 24v I/O (lots of them) analogue inputs for FRO etc and analogue command for the servo amplifiers or if using Step/Dir then I want differential Step/Dir.
The only ones that fit that criteria as far as I know are the products from CS-Lab, Vital Systems and Galil and possibly the Kflop with the Kanalog.
If just wanting a system with 5v I/O and single ended step dir then there is the Ethernet SmoothStepper, the Kflop, the PoKeys, the UC100 etc
So if you could be more specific about the hardware you are wanting to use then suggestions could be more focused, for example will it be steppers or servos, if servos will it be step/dir drives or analogue command drives.
Hood