For now I think both Aston Villa and PSG is in good shape and form and they can defeat any team that underrates team but since they are to play against each other it's going to be a big fight, PSG stands in a better position to win looking at their performance and how they played against Liverpool in both legs, if PSG repeats that dominance against Aston Villa they will be able to defeat them but if they give Aston Villa a little chance Aston Villa with their sharp strikers will not fail to make good use of the opportunity to defeat them. I am rooting for Aston Villa to qualify ahead of PSG this is my own prediction though.
Aston Villa is a big surprise in Champions League this season and they are a newbie here but they have danger of a newbie and underdog. They are not fearful of anything and simply are fighting and enjoying their memorial Champions League season. No fear will be their strongest advantage to fight against PSG that in contrast have more experience in Champions League.
PSG has spent a lot of money to build up their squad mainly for Champions League and they have yet succeeded winning any Champions League title. This season seems to go well for them, by meeting Aston Villa in quarter finals, they have good opportunity to move to at least semi finals. This fixture and the road to final match actually motivate PSG a lot in two quarter final matches with Aston Villa. They are not too far from a second final match in Champions League after many years.
About PSG's motivation, you are not mistaken. But this is not only a wishful-to-be-here tale for Villa either. Emery built this crew not only for sneak in but also for deep exploration of Europe. He is facing his previous club. Asensio’s facing his current club. Lucas Digne still owes PSG some unresolved business. The psychological edges are all over the place. After barely passing through the group with losses to Bayern, Arsenal, and Atleti, PSG had to go to penalties to pass Liverpool. Their form barely clicked recently. Villa's team is fresh, has no pressure, and is incredibly efficiency; every opportunity becomes a goal. While no fear is cute, surgical accuracy and a tactician like Emery? PSG should be really concerned about that