I personally can't put City as favorites to win back 2 back UCL as this is something that rarely happens in this competition. City has a great team but also fights for EPL title which might be an important factor in UCL and Real Madrid is the best team that knows how to speculate games like this and won't be surprised to see Real qualifying further but on the same time I can't see them winning the trophy either.
I will stick with my theory that whoever eliminated Porto in the last years , ended up winning UCL so this year , Arsenal should be one.

Anything can happen, we can see how Real Madrid with 3x UCL trophies in a row then the possibility of Manchester City will fight for the UCL again but certainly we cannot determine that exactly because in the UCL competition it is still difficult to guess even Real Madrid or other teams.
Is it true about that theory? Whoever eliminates Porto they can win the UCL? I've only heard this theory because I honestly didn't notice when the winning team beat Porto first.
Who knows, Arsenal is not the favorite can also happen this season with the title with Arteta.
But, if for example Manchester City is far behind in the race for the Premier League trophy, then it is likely that Manchester City will maximize their chances in the Champion League. Although indeed, at this moment we will also consider the difficult competition in the race for the Premier League title, so we may also judge that it is difficult for Manchester City to be able to divide the focus both in this most prestigious tournament in the Premier League and also in the Champion League.
But indeed, as a team that has quality above average, then of course Manchester City will continue to maximize good results in every match played. But unfortunately, although they have good performance but sometimes they get bad results . Therefore, at least for now we will also still not be able to make a definite choice. Because it is possible that approaching this match later, maybe one of the teams between Manchester City or Real Madrid will get problems, such as injuries and other things that make them unable to maximize in the match.