I also prefer solo riding, but it is sometimes nice to happen along someone out on the roads and strike up conversation with them (if you know them or not). But for me, group riding is a massive PITA. First there's the agreement on the route, then someone has to be 'lead' then you have to just bloody well hope they all turn up at the time and place they promised to. How many times have I agreed to be on a group ride, 'meet at pub x' and 1 or 2 turn up on time then you're left waiting for 20 minutes in the cold for the stragglers, time you could have spent actually riding somewhere. Then, inevitably, there's a mechanical with your riding partners, who don't take the same pride as you do with maintaining their bikes. On a group ride, if one rider has a mechanical - you ALL have a mechanical, while you stand around in the cold (again) while they faff around trying to fix it. The chances of a mechanical on a group ride reaches almost 100% ime.
And after all that, you also get treated to the extra attention by drivers who see a group of cyclists as some kind of challenge.
So yeah, there's the rant of the day.