I know that PSG is in their best form currently, and Madrid is trying to pick form based on the severe injury that the team suffered from last season. From past record, Real Madrid has won PSG and that makes me doubt PSG victory over Madrid. However, Xabi Alonso is not Ancelotti, that I would have said he has a tactics in which he can use to win PSG. Therefore, PSG is the favorite in that match.
Xabi Alonso has so far shown that he is able to manage Real Madrid quite well. because we don't see a decline in quality in the Real Madrid squad even though Xabi Alonso is new here. But he is like a coach who already knows the Real Madrid squad well. However, we still cannot be sure about Real Madrid's performance whether it will be consistent enough or not. As for PSG, at least they have proven that they have quality that they can maintain so far.
A very fierce match will really make it a match we shouldn't miss. The sensation of the final match will be felt in this match even though it is not the final. But I think these two teams are the strongest among all those remaining in the semi-finals at this time. But yeah that's just my opinion and the reality is later after we see the final result.