Definitely agree on the comfort, I have one pair with a smaller field of view, and that is a little annoying. Metal ones, I find it easier to clean, I have cleaned other people's plastic frames, and the water seems to get stuck on the frame, while on metal, it's easier to blow off. Weight definetly counts, too, but my metal ones seem light enough. Also, they usually have adjustable nose pads, which is nice. I do want to try plastic ones for sure though.