Real is stronger now, it was evident from the first match, City are good in attack, but they have problems in defense, and this is their weak point, and with such attacking potential as Real it will be difficult to resist. City today only needs a win, but Guardeola has a very difficult time playing away matches in the Champions League, and they also need to pay attention to defense so as not to concede.
Compared to Manchester City, Real Madrid has better defense, even they lost many defenders, but at least they have Courtois. Unlike Manchester City, many of the defenders are under perform. Ederson, isn't a great goalkeeper, he's only good in build up and long pass.
I'm not sure about Dortmund winning, although they purposely lost their last game to an underdog in the Bundesliga to save their strength for the battle with Lisbon... I think that the guests will try to win or there will be a draw... About Madrid, I also think that both teams will score, but Real will not miss the chance, that's for sure... One goal is not a big difference and Madrid will need to score more...
Yeah, when the team leads, usually they choose to play defensively or not trying harder since they know they will qualify to the next round. Dortmund might play defensive since Sporting Lisbon can't be underestimated, but this won't work on the other match PSG vs Brest, PSG will play offensive.