I lived in AMR II during my freshman year, but spent most of my time with my friends in Wolman. My floor/house of AMR II was socially dead, everyone kept their doors closed, and there were people who lived two doors down from me that I never even met throughout the entire year. So the AMR's aren't necessarily more social, its just what you make of it. The good thing about it is you can walk throughout the entire building pretty easily, and meet other people outside of just your floor and house.
If I were to do it again, I would live in Wolman. It's almost unfair how much nicer it is than the other freshmen options, the largest rooms, air-conditioned, with private bathrooms. You also get a common room with couches, tables, and a tv, and people hang out there all the time, which really allows you to bond with your floormates. Downsides would be that you have to clean, and you probably won't interact too much with other floors.
Buildings A&B, at least for my year, were known for being socially dead. That could change, but if you want suite style living go with Wolman.