Hi, Meeshell, Welcome to the forum. I have walked from Montserrat, but I went via Huesca instead of Lleida. You can see the two branches here (but you of course may already know this)
https://www.gronze.com/camino-santiago-catalan Based on what the forum members who have taken the Lleida variant have said, I think the Huesca alternative is probably nicer. After Huesca, the scenery is beautiful (before, not so much, but I walked in June when the crops had been harvested and things were all some shade of brown). The Huesca alternative also gives you the not to be missed opportunity to visit the monastery of San Juan de la Pena and the possibility of heading back up to Somport to walk the Aragones, which we did. The ARagones is not very popular, for some reason, but it is beautiful.
If you go through Lleida, you will merge onto Ruta del Ebro, which I walked a few years ago. That's also a very nice route, but again, I think a variant is the better option. Instead of continuing on the Ebro all the way into Logrono, I turned off a few days after Zaragoza to get on the Castellano Aragones, which is one of my favorite solitary caminos ever. But not one I would walk without a GPS. If you look at the schematic Gronze map, all of these alternatives will be much clearer than my rambling.
https://www.gronze.com/#todos
It's of course not for me to tell you which route to walk, but just in case you don't know about the alternatives, I thought I'd throw them out. And one more thing -- have you considered starting before Montserrat and walking the Cami St. Jaume from the French border, through Girona, Vic and Manresa to Montserrat. Now that is one lovely walk, with LOTS of unbelievable romanesque churches thrown in if by chance that is an interest of yours!