PSG vs Arsenal would surely be a tough one to predict. PSG barely won over Aston Villa and Arsenal surely is playing better than Aston Villa. PSG's recent league games has mostly turned into draw or loss even though they already have a large points lead.
Among Barcelona and Inter, Barcelona should easily win it as they have one of the best European team.
I prefer PSG to win the first leg because none of their squad is injured. PSG has performed brilliantly this season, many football observers think that this season PSG will succeed in becoming champions in the Champions League.
Arsenal is indeed very strong but if they meet this season, of course PSG is superior and they have a strong mentality to advance to the final. I think if PSG manages to score an early goal then they will succeed in becoming the winner in the first leg. But if arsenal manages to score an early goal then their enthusiasm will be even more intense because they are playing at home in the first leg.