Well, I can’t vouch for either one of the Manchester clubs because City have not shown that they are a better team than they were last season and United are still finding the balance. So for me I think it is a 50:50 game in the derby, either sides could win. This game could also be the turning point for City when the league resumes you just can’t tell.
Judging from their previous games in let's say 10 years back, Manchester City had always had the upper hand so definitely the bookies will give them a lesser odds compared to Manchester United. Few years back, there was this game between these two clubs and Ten Hang was still in charge of Manchester United, City were of course the superior team, in that very match Manchester City scored first but at FT Manchester United won the match 2 - 1 after they scored two late goals. Again in the FA cup finals, of course City were also the favourites but at the the end United won the match. These are two notable that I brought to your notice, City has been the favourites to win among the two teams in recent years but sometimes surprises can be pulled that's why I'm agreeing with Satoprincess on the 50 : 50 for both clubs.
My dear, I don't think the bookies would judge them with their previous meetings 10 years ago, cause their both squad currently is different from what it used to be 10 years ago, they'll rather rate the odds, judging from their past 5 meetings and present form, judging by that, one could say it's either 50:50 or City is slightly greater than Manchester United.
However we should always acknowledge that it's a derby, the Manchester derby for that matter so both teams are going to show toughness, I believe that both managers are cracking their heads on how to win that match since there's much pressure mounted on both of them, they're seriously watched by the media including pressure from fans.
In the last 10 years, Manchester City has been the more superior team between both Manchester clubs but before the era of City's take over, Manchester United were superior, correct me if I'm wrong on this. If you check the last 5 meetings, 2 draws, 2 wins for United and 1 win for City, by contrast Manchester United should be superior, check this season's form as well. Check their position in the league table, Manchester United is ahead of City which means, so far this season, Manchester United is having a better form compared to City. With all these, Manchester United is supposed to be having a lesser odds compared to City, now do me a favour and check any bookie of your choice and tell me the odd you will see there. Bear in mind that if it's the last previous meetings, Manchester United should be superior because they have more wins than Manchester City between both of them.