I would bet on Inter to win the match because they are in a good form compared to Milan. Milan is facing some challenges which is affecting their winning mentality. When it comes to a time like this is a competition, Inter is always deadly because they always want to be the best. Milan might pull some stunts but I am not expecting any surprise from them. However, it's gon be a tough match.
Inter is indeed in better condition and the last 5 weeks in Serie A show them in a positive trend compared to Milan but remember this is a semi final match and we also have to consider the rivalry of the two teams besides that if we still remember Inter defeat in the Italian Super Cup final we have to consider that Milan could do it again.
Let's see the opportunities given by the bookies.

The chances are quite high for both teams and even for BTTS the bookies give odds @1.80, I doubt whether both teams will be able to score.
This is the last opportunity for AC Milan and it isn't looking great for them as I doubt there is a possibility for them to get a good result in neither of the two legs. If anything then they have to win this game and give themselves a good position for the second leg because that is going to be even harder.
AC Milan doesn't have enough top players and too many of those players are too erratic. Pulisic is one of them and there is a reason he never stayed with the same club for long. He can be one of the best if he peaks in a game, but he can as well be one of the worst and ineffective.
Against Napoli it was ok, but the ineffectiveness killed them again. Chances were there, but nobody to use them. Players like Joao Felix and Pulisic are supposed to give their game the additional effectiveness they need, but they don't.