I prefer chiclet style keyboards when I am coding, and mechanical keyboards when I am writing. The clack of the keys acts as a sort of white noise to shut out the world and allows me to think about what I'm writing more clearly.

When I was able to write in coffee shops and the like, I didn't want to bother other patrons with a noisy keyboard, so I whipped up my own writing app that simulates loud keys via headphones, and it works almost as well as the real thing.