I will be repdicting Roma to win Porto and Mancehster City to win Real Madrid.
As for Roma vs Porta. i firmly believe Roma will win it. Although it's gonna be a hard game, it's following they have only home game as their morale booster. However, i'm not a fan to bet on one side, much prefer to take BTTS. I expect porto does parking bus that makes them struggle to score.
They often struggled to score against low block team in serie a, and i expect the same thing to happen as Porto has to do everything to ensure they won't knocked out from Europa League.
Not sure about parking the bus because the result in the first leg was 1-1, so they will still play openly to score first. So, whichever team manages to score first, then it will make them play more defensively to maintain the score and aggregate. But, if it is said that Porto will play defensively from the start of the match, then I am sure that is impossible, because Porto will also try to score first, with an open playing pattern there will be a chance for both teams to score. But yes, I am also confident that AS Roma will succeed in qualifying, somehow the process is determined until the penalty shootout or can be determined only with 90 minutes.