It will be a very interesting match! As a Feyenoord-fan I'm really quite neutral. In general I would hope that Ajax wins, but since we would have to split the Champions League-funds with them, for Feyenoord it would (in the short term) be better if United wins. The decisive factor for me is however the attack of Monday, I think it would be appropriate if Man Utd would win the cup tonight.
Ajax has quite a good squad, by far the most talented one of Holland, but they've been very vulnerable in away-games (they have lost all away-games in the knockout-stage this season). But that could also be because Ajax had already made a difference in the home-matches, and they're not good at handling that pressure (which won't be a problem tonight, since there's only one match). Hopefully Onana and Traore can play, it would truly be bad luck if they (and especially Onana) would miss the final.