Always a controversial question but back in the early 1900s there was only ever one answer and that was Manchester City who were often referred to as simply ‘Manchester’ in official publications for both City and their Manchester rivals. Here’s an image of the title section of the official programme which directly references ‘Manchester’ (meaning City) and Newton Heath.
Obviously, as there was no Manchester United then I guess it was inevitable that City would be known as Manchester to some. It just surprises me that an official publication for both clubs would use ‘Manchester’ so regularly. Presumably both clubs were happy with this. So if anyone asks ‘which club is Manchester? then the one both were happy to call Manchester must be in with a big shout!
On another topic… notice the opportunity to have your flask filled up at City’s headquarters, the Hyde Road Hotel, before the match? Imagine if that option was brought back at the Etihad!