Both Real Madrid and Dortmund deserve to win the title. They have performed impressively in UCL this season. Although Dortmund only finished in 5th place in Bundesliga, they showed something different in UCL. Sure, Real Madrid looks better, they also becomes the champion in La Liga. But I think the performance in domestic competition won't bring much impact for the UCL final match.
I also think it will be a tough match. Real Madrid looks having better attackers but Dortmund has strong defense. It won't be easy to beat Dortmund if they have no problem with injured players. A German team is very often unpredictable when it is in international match. Just remember that Real Madrid was almost defeated by Bayern Munich in semi-final! Real Madrid must be more careful to play against Dortmund although they are more experienced in the final UCL and have cool stats.
Dortmund indeed still has the opportunity to get an UCL title but for me the biggest opportunity in history is only Real Madrid who can get the UCL title this season.
maybe I am too ambition as a fan of Madrid but logically I am very confident from the difference in the quality of the players of both teams and different performances.
as you said if Madrid has a very strong attacker but Dortmund has a very sturdy defense, but believe it or not, Madrid will easily knock down the strongest defense that Dortmun has.
now let's look back at the appearance of Bayern Munich and if you see the defense of Bayern Munich and Dortmund actually the two teams from the Bundesliga have an almost equivalent defense and see how Madrid destroys the defense of Bayern Munich through consecutive attacks in the second round from the side and managed to get 2 score.
this can happen when fighting Dortmund and if you recall how experienced Madrid must always have a lot of tactics and strategies to continue to score and defeat their opponents.
I understand if the performance of the domestic league will not affect the UCL match later but if you see Madrid appearance in the rest of the match before this season ends, you will see how strong the second layer player has Madrid and that is only the second layer player, then what if the player main playing in the rest of the match?
well, from this statement I am still sure if Madrid players are of higher quality and can get a title in the final match later.