The record of the previous meeting is actually not too important in the upcoming match, but usually the team that is dominant in winning the match is the one who wins it the most. So I think Barcelona are the favorites in that match based on their head-to-head record, but I don't think Barcelona can be completely relied on in Europe this season after they failed in the Champions League.
This season, Barcelona has had pretty good results in La-Liga, despite difficulties in European competition. However, MU position is worse, both in Europe and in the EPL (now look like better). This is then makes me believe if Barcelona has a better chance of winning than MU in the upcoming match. H2H is superior to Barcelona, but that's not what I see, but the current performance. However, an H2H that is not matched by the current good form will be history.
Let's see how it is going on. I saw bunch of people last year said the same thing as you when barcelona faced frankfurt, Mu is doing so well in any of EPL matches. Barcelona may have good result in head to head against MU but i think that the chance for both would be the same.
There will be so many surprises going to happen when MU will be against barcelona. I pick MU in this case. Barcelona looks strong enough but i think that i will be risking myself with it.
The match is still very long to go. I hope that there will be so many improvements to be happened with MU
Head to head predictions in this game will not be correct, currently both team are inform, but Manchester united has more advantage in teams of quality players than Barcelona currently. And if this match is fix today Manchester united will win Barcelona will high margin.