When you talk about Man City's most important player it is hard to look past Vincent Kompany.
Physical
It's intriguing to compare City and United's squads, too.
David De Gea has improved a lot since he joined Man United a couple of seasons ago, bulking up and getting used to the demands of the Premier League, but I would still rather have City's Joe Hart as my 'keeper because he is a great physical specimen.
However, if I was asked to pick between the strike forces of City (Aguero, Edin Dzeko, Alvaro Negredo and Stevan Jovetic) and United (Wayne Rooney, Robin van Persie, Danny Welbeck and Javier Hernandez), I would go for Moyes' options.
There's not a lot in it but all four of United's strikers are proven in the Premier League - some, of course, to a bigger extent than others - whether that's starting games or coming off the bench to make an impact, but a few of City's forwards still need to show they can cut it in England.
Selecting the best striker amongst those eight names is tough and you could argue that it is Rooney, who played extremely well in the Champions League against Bayer Leverkusen on Tuesday night and can operate in the hole or right up top.
But I would say at this precise moment it is Van Persie, who has had a few great years stretching back to his time at Arsenal and was probably the deciding factor in United winning the title last year.
