Barcelona have the advantage because they beat Benfica 1-0 in the first leg.I think Barcelona will not lose in this home game.Barcelona will be the one to go through.
Liverpool had a good chance in the first match and managed to win with a goal in the last minute.This time things may be different because PSG was really dominant in the first match and wasted many positions.So if they can show the same game again, they may have a chance to pass the round away.
Barcelona 1.44 vs 7.00 Benfica ( Barcelona win)
Liverpool 2.40 vs 2.90 PSG (I'm not picking one of them)
Barcelona's game is one of easiest game to predict. They will lead the game with one goal aggregate, which is obviously giving pressure to their opponent. The only problem is that they may not in good mentality after the doctor closer to their players was death. This reminds me when the same situation happened at 2013. They have to put it aside to ensure it won't impact their performance.
As for Liverpool vs PSG, i'm not really sure which side is gonna take the advantage in this game. I know Liverpool leads with one goal aggregate, but their gameplay was terrible in the first leg. They may be losing the game if they play same like what they did in the last week.
I hope there will be some changes from Liverpool's strategy. They can't really play defensive strategy again.