Personal preference; they all have their pros and cons. Galvanized waterers last a lot longer than plastic, unless you dent or bend them. You can't put apple cider vinegar in galvanized waterers, only plastic. If you purchase, be sure it's easy to take apart to fill and clean (don't ask me how I know.) Plastic waterers that are designed to be hung from the ceiling tend to break easily, and do better set on blocks or whatever. Chickens will stand and poop on tops if there isn't something obstructing them. I keep a string tied to the handle on my galvanized waterer, for example, which is also tied about 3' above it; otherwise they stand up there and poop in the water. Plastic does not hold up too well if in the sun for long hours.
I've never made either. Looks to me like a waterer would be trickier than a feeder.
I'm sure there is a lot more info out there on the subject.
Hope this helps.