And let's look at what Mercedes has:
Hamilton - I would consider this a positive given his pace, without getting into a debate on whether he is better than Schumacher in his peak or whether he can build a team around him.
Mercedes - I am not sure if Mercedes will fund this team to the same level as Ferrari did or whether this is possible or would have the same benefits given the RRA and testing restrictions. There is certainly a correlation between a larger budget and level of success; HOWEVER, Honda is a rather egregious example of having consistently broken this correlation. And as far as one can see, things do not seem to have changed much in terms of management since the Honda days.
Elliot, Costa and Willis - Even their combined might is nowhere near Byrne's legacy (even when giving due credit to Costa as Byrne's deputy at Ferrari during the dominant days). The ongoing development and the latest Singapore updates to the W03 certainly do not suggest otherwise. But I guess the truest test would be the W04.
Brawn the strategist - One would be forced to assume that age has caught up with him given the strategy calls at Mercedes (assuming he has indeed been behind those calls). So it's a walkover for Ferrari Brawn over Mercedes Brawn.
Brawn the TP and Mercedes race team management overall - Cant even be mentioned in the same sentence with Todt. So far, the management decisions at Mercedes and their top management structure has not made any sense whatsoever (including the latest Lauda hire). The decisions have been so counterintutive that had it produced results, it would have been heralded as a new paradigm in management theory
And the results so far dont suggest any new paradigm!