I would prefer schooling. I’ve had gold barbs and neons that we’re pretty close knit swimmers, but neons aren’t great for harder water and gold barbs just aren’t real mid tank swimmers in my experience
My gold barbs were by themselves in a 55 for years. I don’t think they were stressed. I know some stick together for other reasons like group breeding. X-ray tetras seem nice, but no one seems to have much experience with them.