Yes I know this is soccer and it is also a big league as well as that Porto is not a small team in the domestic league and I really understand that the ball is round that anyone can get a victory on their own abilities, but even though Porto often participates in the champions league, but compared to that we know that Arsenal is more popular and wilder in the ears of football fans, and maybe we realize how much distance between Porto and Arsenal when compared to each other.
Although with my selfish thoughts it must be admitted that Porto deserves to be considered, their ability is very unpredictable, even with a victory with a goal difference of only one enough to secure the match, and the next match if Porto can hold a draw, Arsenal can be eliminated by Porto in the UCL this season.
In terms of team mentality when competing in the Champions League, I don't think Arsenal and Porto have a significant difference, but it must also be admitted that in terms of team quality, Arsenal is slightly better than Porto this season.
And regarding Porto who were 1 goal ahead in the first leg, this is quite natural because they are playing at their home ground, so in the second leg Arsenal will play at their home ground and also have better strength than Porto, so this opens up possibilities. Arsenal were able to turn things around in a big way.