I've used polyester (Agfa, Fujifilm), thermal metal (Agfa, Fujifilm, Kodak) and violet metal (Agfa). I have to say that for consistency, service and reliability I very much prefer Fujifilm LHPJ thermal metal plates. I have had lots of success with Agfa thermal and polyester plates I used as well.
Polyester is awesome for short run work that does not have extremely high quality standards. It is sometimes challenging for press operators who are used to metal plates to change over. Operators tend to want to stretch the plates and use chemistry that isn't friendly to the polyester plates. In the past I successfully switched a small 4 press pressroom to polyester from metal with substantial financial savings.
Violet plates tend to last longer but require safe light. Violet plates require nasty chemical processes or at least last I heard the "processes" violet plates were still in R&D despite years of "next year" announcements.
Thermal plates are daylight safe. Thermal plates typically do not last as long as violet plates. Baking thermal plates can increase run length.
As far as imaging devices today there are basically 3 main manufacturers: Heidelberg, Kodak and Screen. The screen machines are rebadged and sold under various labels (note the companies that I didn't mention - they are likely selling Screen). I've used Xante, RipIt (now part of Xante), Kodak, Heidelberg, Agfa and Fujifilm machines. Every machine I have worked with has been very reliable except the Xante machine. I personally wouldn't even answer the phone for those guys if they wanted to give me a machine for free. As far as post-processors almost all of them are made by Glunz & Jensen. Different vendors have different configurations specific to their plate technology.
