Milan vs Napoli match which will be 50:50. that's because before Napoli could be superior to Milan, but in the previous meeting Napoli were destroyed 0-4. this makes the fight will take place unpredictable. both are pretty even.
but for Madrid vs Chelsea. I don't think Madrid will suffer. at least in the first leg Madrid will win. and in the second leg they will only defend. although I know, sometimes matches in the Champions League are very difficult to predict.
why it's not easy to guess because now the UCL has reached the quarter-finals and maybe if it's in the group stage it's still predictable, but for the quarter-finals to the final it will be difficult because all the clubs that qualify always have the opportunity to surprise, just look at yesterday everyone thought that in the league match Napoli could beat Milan, it turned out that Napoli was beaten with a score of 4 goals without reply and that is what makes predictions still difficult, talking about Chelsea, who just left Potter because he was fired, of course it can also have other effects for Chelsea's game later, no sure they qualify to beat madrid who are currently in good form
I think every team that qualified for the quarter-finals is strong enough. And we have seen in the past that under-favored teams win in quarter-finals or semi-finals. And so no team should be considered weak in the quarter-finals. Chelsea, Milan or Benfica could be considered somewhat weaker, but each team has the ability to qualify for the semi-finals. And if their opponents make any mistakes, these teams will be able to qualify for the semi-finals. So even if the teams are strong, there is no guarantee that they will win.