depends on preference (up or sideways) | motherboard | case and budget.
as mentioned the Hyper 212+ Evo is nice..
Z68 Gen3 board is still a quality move, I have a variant of that Gigabyte motherboard myself.
what's your GPU configuration and your going with what, 2500K.?
First of all, you have to be able to even get a 680, which seems almost vaporware as availibility, then you have the big K right around the corner?or (and I hate to say this....) get a GTX 570 on sale...
with the way nVidia are releasing (lesser performing) chips as upper level GPU's because of Radeon's lack luster performance,
odds are nVidia will continue to do so and in the end....
GTX 570 or GTX 580 (super sale) will be acceptable.
(for me anyways)..