Level of noise
The level of noise is always different in different company cultures, departments, and office designs such as open offices. There are few lucky ones, who can fully concentrate in a noise environment too, but for most of the people, high noise affects productivity in a negative way. Overall, the distraction can be eliminated with the help of headphones, provided by the company and suitable for all computers. Also, shared Youtube or Spotify playlists can be created with concentration boosting music recommendations for focused work (white noise, classical music, deep techno, etc.).
After providing these inevitable factors, you can adapt elements that are not amongst the minimum requirements, but their presence can boost employee satisfaction.