I don't like metal dishes. Personal feeling really is all. I did try them back years ago but didn't care for them. They just seemed to get smelly. Hard to clean. And too deep for a cat's face anyway. Glass won't cause allergies, easy to clean, less likely to harbor bacteria. I know a lot of people use metal but I am not a fan. Even stainless steel scratches, giving places for bacteria (and odors) to harbor and....to me..just doesn't seem to get clean enough. And you have to be careful about where they were made. Glass/china you also have to be careful where they were made of course to ensure no lead.