The Europa League remains the most unpredictable tournament, and if we started talking about Benfica and Marseille, then this is also an unpredictable pair for me.
Football is unpredictable in any match even between a strong and a weak team. There is always opportunity for surprised result from a weaker team.
Prediction on a tournament with participation of many clubs, is harder and more unpredictable. Gamblers can reference data and make predictions, then bets, but no 100% win rates for them.
Benfica and Marseilles are equal in quality and their matches in quarter final are hard to predict result accurately.
Benfica on the other had has been fair in their performance in their domestic league and has not been doing poorly although they are average but they are more consistent than Marseille has been this season even in the Europa league games so far they have been much better than Marseille has been but Marseille has been fortunate enough to get to this stage and this may be the end of their journey.
Ligue 1 is still a bigger league than Portuguese League but Benfica are one of two strongest clubs from Portugal, another club is Porto. They are very experienced with tournaments in Europe from Champions League to Europa League.
With their experience, they will not be much weaker than Marseille in quarter final. Benfica have good players too and they are well-known as a transitional club for youth players before they matured enough and can move to biggest clubs in Europe.