Not many aircraft have a bright, mirror-like chrome finish, so the aluminium would, in my opinion, be more appropriate more of the time. Having said that, the chrome can be burnished with a rough cloth or wire wool to make it less bright, but still glossier than the matt aluminium. They do 2 types of chrome - Chrome (sometimes called Improved Chrome) and Ultra-bright Chrome.
It's expensive, I know, but it really is worth practising on a scrap model before you embark on your masterpiece.