Lee_avce,
I suppose it is clear by now that your question is not very specific! Did you want to know what are the alternatives for NOT using PLC's, or did you want to know some alternative PLC brands?
Some popular brands in the U.S. are Allen-Bradley, Siemens, and Automation Direct.
The alternatives for not using PLC's have already been discussed by others, but probably the LAST common method used before PLC use was wide-spread was the electro-mechanical relay control box. I remember that in 1979 I helped build a relay control cabinet that had 110 relays. It controlled a lock hopper for a gasifier. In fact there was a problem with the system, but the logic had became so convoluted that none of the engineers could figure out the problem. Finally in desperation, I attempted to simulate the logic on an early desktop computer, the Apple II. I wrote a BASIC program that simulated exactly the relay schematic diagram, and finally did uncover the bug.