We did a bunch of these threads during covid confinement. The “leader” would put out a stage (which many others then would modify, comment on, add to, etc) and we went inch by inch along. You’re right that it’s random. In terms of structure, there is no way to keep the discussion completely linear when people are in different time zones, remembering different things at different times, etc. So it was a lot of fun for us, and gave people a lot of good ideas, but maybe not so helpful for those who come after us. Anyway… on to your question about the choices.
JP is right that Monserrat to Lleida will have more pilgrim infrastructure. In fact, the other two options have none or very little. I did the Huesca variant, so I only did a stage or two from Monserrat that overlaps with the Lleida variant. Those first few days had a fair amount of road walking, and after Monserrat, the natural environment wasn’t as spectacular.
Vic - Monserrat has those days in and out of Manresa that are not so great. It all comes with the camino, of course, but if you’re only walking 4 or 5 days, it would not be my choice for a sampler.
Girona-Vic is in my opinon the most beautiful by a long shot. And if you take the detour to St. Pere de Casseres, you get the extra treat of the romanesque monastery of St. Pere de Casseres and the neolithic sites that were really fascinating. But I would agree with those that say it doesn’t really have much of a Camino feeling. What it’s got is the scenery, the architecture and it’s bookended by two very nice places.
I don’t think you’re likely to meet any other peregrinos on this route, but I loved it all!