I am quite sure that noise level is a personal preference. I know people who use industry grade ear protectors (only few) and much more who just use headphones

I am quite sure that noise level is a personal preference. I know people who use industry grade ear protectors (only few) and much more who just use headphones with loud music. Note that open office is not only about noise, though. My answer would be - open office is the best, as long as you can have quiet time when you need to focus (headphones, protectors, whatever suits you.)