Unless Aguero is in his beast mode form (about a couple of months a year), there's nowt much in it between our respective first elevens tbh.
Where they may have an advantage over us is that they have a deeper squad, thanks to them being able to keep 140 k a week players on the bench, something with our financial situation compared to theirs, we can't do. *cough Sagna cough*
I also don't think Pellegrini's as good a manager as Wenger though and additionally, like us in the past, their mentality isn't as strong and resolute as could be and can be prone to collapse when things go wrong ..... it's probably more of an issue for them considering that a lot of their team are just mercenaries.