Predicting the Atalanta vs AC Milan match will indeed be quite difficult. Because on the one hand, AC Milan is a strong team and even though they have experienced setbacks, in the last few weeks we have seen that AC Milan has not experienced defeat and they even had a big win in the Coppa Italia round of 16. So Atalanta really has to fight harder to beat AC Milan. But Atalanta in this match also has the home advantage. So favoring Atalanta might also be a pretty good choice. But yeah, I'm the same as you, feeling confused about which team to favorite. Because both of them have teams whose strength is worth considering.
AC Milan will clearly have difficulty in the match, in addition to their inconsistent performance, their players have not been able to match the frequency of the coach wishes in implementing the strategy. Atalanta is stronger, more stable and the advantage of playing at home is a complement that their target of getting 3 points can be achieved. AC Milan is still not promising and I would not be too brave to bet on their victory.