If Real Madrid can play with full team and Benzema has no bad issue (injured), I also think that Real Madrid has a bigger chance to win. Benzema looks to play better than Lewandowski, and other Real Madrid attackers look more productive than Barcelona attackers (scored more goals). In this matter, we can assume that Real Madrid has a better attacking line. For midfielders, I also think that Real Madrid is better than Barcelona. It is only about the defenders, if Real Madrid defenders perform well, Real Madrid should defeat Barcelona. In the previous match, Real Madrid defenders played under performance.
Yes, even though they are superior, there is no guarantee for Barcelona to beat Real Madrid again. Real Madrid visited Camp Nou with high ambitions to steal victory and qualify for the final. Carlo Ancelotti is aware that only the Copa Del Rey is the only domestic title his team has the chance to win, because for the La Liga title it seems that hope is very slim. Xavi certainly has to be wary of the drums of war that Benzema and friends are beating, because Real Madrid has good capital after winning a landslide victory over Valladolid.
all possibilities are still very possible for Agg to be left behind by 1 goal in the first leg, of course it's not that burdensome for Real Madrid and I think that if these two teams still have the same percentage to qualify for the next round.
and for the strength of the team, I think there is not much difference between the two, but whoever is better prepared to perform better will probably win because materially the Barcelona or Real Madrid players are very evenly distributed in every line.
This is certainly still very winnable for Real Madrid. I personally don't believe Real Madrid is going to lose just because they have a disadvantage of 1 goal. Real Madrid have a good experience of making comebacks in the second leg. We have seen that multiple times, especially in the Champions League. Real Madrid already knows that they don't have much chance of winning the La Liga title. So they will shortly try to win the Champions League and the Copa del Rey for sure.