I feel confident that if Barcelona play in Spain, Barcelona will win. Team wise they are better than Man United for now. But the distance of the game is still very far. They will pass the transfer market and the world cup. Maybe there will be a lot of surprises in the transfer market later.
In terms of quality and cohesiveness the Barcelona team is superior to Manchester United, Barcelona also appears consistent in the domestic league. The comparison of the sharpness of the strikers of the two teams also gives Barcelona an advantage, but Xavi must remain wary of Manchester United's strength.
Barcelona must use the first leg to score as many goals as possible, Barcelona has also started solid again after the defeat to Real Madrid. Barcelona defense has improved, in fact Ter Stegen has kept 11 clean sheets from 13 games in La Liga.
I consider Barcelona as the favorite in Barcelona vs United match. Because the Barcelona team may have played poorly in a few matches in the Champions League. But they have managed to maintain their dominance in La Liga. On the other hand, Manchester United's performance is not stable. They are not playing well in the Premier League. At the same time, despite winning a few matches in the Europa League, their performance was not good. Manchester United have also had a lot of trouble winning against weaker teams. And so I don't think it is possible to win against Barcelona with such a shaky squad.