If you want to go generic, go with MCE, it's the most stable quality. The next best is VCI Vision. Stay clear of PLC, except JRT. PLCs aren't really designed specifically for elevators, they are more like general purpose relay controls emmulated by a solid state controller. While I actually would recommend them in hazardous locations like mine shafts and jails; however I would not recommend them for a group of elevators, the quality of the dispatching is like that of an old Westinghouse or Express lift, where they tend to go chasing after each other. You might could get away with just a single cab. They also require a lot of wiring, which is trial and error.