I enjoy group rides when the people I'm riding with are competent riding in close proximity to other riders. Riding with folks who are nervous and uncomfortable in that situation is going to have me looking for an exit very quickly. The pace could be social, or it could be a hammer-fest - I enjoy them both. Getting down the road quickly, in a tight group working together, is one of my favorite cycling experiences. My typical Sunday group road ride is a casual pace (zone 2-ish tempo) for the first half, and then we dial it up and get spicy, playing the game of bikes to the ride end. It's a really enjoyable mix. I enjoy riding solo, too, but more so in the dirt (gravel or MTB) than on the road. Getting dirty with a friend or two of similar abilities is always a really good time.