It all depends on what you're planning to do with it. If you're leaving it stock to mildly overclocked then a CM 212 Evo will suit your needs. If you are really looking to push then you will probably need something better.
I own the following:
CM 212+
Thermalright Ultra Extreme, bought used on Ebay for $20+ S/H which gave me 8c better temps then the 212+ on my I5-2500k overclocked
Prolimatech Megahalems, also bought on Ebay used for $15.+ S/H, it gave me 10c better temps on my 2500k overclocked.
Take my drops in temperature with a grain of salt, they aren't scientific tests and I didn't check for differences in ambient temps, though the test were all run within an hour or so of one another, with the same fans. YMMV.