The match is indeed and unpredictable match, any team can win at any point. If you wanted to use the quality of the squad to make conclusions, you will realize that they both have similar qualities likewise the two coaches too. Real Madrid can only be ahead of Manchester City because of Real Madrid has won more Champions League than Man City and with the nature experience players they both have, that alone cannot count Man City out.
In fact, all the quarterfinal matches will unpredictable and will contain good offset.
This is true, most of the matches, if not all in the Champions league quarterfinals will be unpredictable and an example is between Manchester City and Real Madrid. When you take a reflect at the last fixtures both team had, Manchester City have been more consistent with winning over Real Madrid, including the last game both team played together which Manchester City scored 4 goals over none of the Real Madrid.
But when you relate those matches with the current performance of both teams, Real Madrid is already at the very top of the table standing making them the leading club of the league. Whereas Manchester City is still battling at the 3rd position of its league. If you are to judge by the present performance of these clubs, you will suggest more that Real Madrid has more chances.