I prefer the Battlefield serries. The multiplayer in CoD is too repetitive for me. It's gets boring when every match is the same. In battlefield, every match is different. It's much more realistic then CoD and just more fun to me.
I would say 50/50. A lot of Sandboxes, but not enough that every map i play on is forged by somebody. But if there are lots of sanboxes then there needs to be a large variety of themes and peices.