I think nylon is quieter for sure ... but I tend to split them. I haven't done that in awhile, so perhaps the quality of washer is getting better.

I'm definitely not into replacing all my steel washers with nylon ... and I actually prefer steel because of their durability and accessibility.

If anyone uses a loose turning on your toms, etc., then nylon may be something you would want to check out. I'm sure the whole purpose behind nylon washers is the unwanted, sympathetic vibrations.