- CM Hyper 212 Evo will get you standard to some OC
- Scythe's Mugen 3, preferably the Rev B PCGH edition, will get you some more for about the same price
- Noctua NH-D14 is the top, but also a lot more expensive
- Be Quiet Dark Rock Pro 2 is as good (and expensive) as the noctua, but more silent.
Take your pick, get some Arctic Cooling MX4 paste and you're good to go.
EDIT: lot's of liquid recommendations here, also a good choice, but only worth their price if you really want the max OC