No overclocking, Intel stock operation* [Caution! Some motherboards do not follow Intel stock operation out of the box; they are tweaked for some extra performance already... but they will run warmer because of that.]:
Air: think dual towers, like NH-D15 or similar, and large single tower, like Thermalright's Le Grand Macho RT or similar. There's also the unique NH-U12A which can rival the larger models.
Hybrid: 240mm performance or larger.
Possible overclock, or use of 1-click OC features:
Air: Just skip it.
Hybrid: 280mm performance* or larger, and custom liquid. [There's 2 different types of hybrids, performance and low noise. The latter does just what it says, but sacrifices performance. Should be avoided for overclocking, as they serve a different purpose.]