The 2000 is the tall one (25"H x 25"D). The 1200 is the long one (20"H x 25"D). The 1000 is the same height as the 1200 but not as deep (20"H x 20"D). The 1000 does not provide enough room behind the power supply for modular cables, so I am going with the 1200, though admittedly 25" is pretty long for a case. Two cases I have now are both 17"H x 19"D but they can only handle 4 hard drives and I need 6.
That's one reason I am torn on the options. It seems silly to buy a large case with plenty of room and nothing blocking the motherboard, only to then block the motherboard with cones to direct air. Of course if it makes a big difference in cooling, it might be worth it. I am also wondering how easily these things swing out of the way. Also is the BplusII the same as a B with the options added, such that I could get the BplusII and remove the options if I don't like them and have the same thing as if I had got a B to begin with?