Don't get me wrong, I will eat either, but I do perfer spare ribs.
I tend to think that spares have more meat by volume if not percentage and yes I am counting the fat as meat. I think that BBs may be more lean or possibly have the fat more evenly distributed to give me that opinion. There is knid of a conception that BBs are maybe the more sophisticated or civil version of ribs and I think that alot of folks follow trends. But for me, there seems to be a more primal animal in nature urge to eat the spares. Maybe a survivial of the fittest type thing, the ole bigger is better mentality. Another thing that I have noticed about BBs is the potential for the fall off of the bone faux pas (Never really stopped me from eating them though as long as the meat didn't fall to the floor) While the fall off of the bone issue does not really hurt things if you are sitting at a table and eating with a fork over a plate, it can make walking and snacking difficult. Another thing that I have noticed is that if sause is applied while BBs are still cooking, it seems to completly soak thru the meat and some cooking methods make it seem like the sause even soaks thru the bone! I think that the size and texture of the cut lends to this happening quite often with BBs, but the larger size if spares kind of makes this happen less often or to a lesser extent.
To be honest, spares are kind of the bigger uglier ribs because I don't trim them down much. I don't serve them on a plate in a half or whole rack presentation, I just cut them apart and pile them into the biggest bowl or platter that I have and yell "Dig In!" If you want to sit around and eat BBs that fall off of the bone with silver forks and fine China, no problem. But me? I kind of like sitting around with the cave clan grunting and gnawing on great big ole bones.