Heres the deal:
The CM212 and the Phanteks will perform exactly the same with the exact same fans and thermal paste because you really can't get much better for a tower heatsink with push pull.
$30 for CM212 gives you a cooler with a really crappy mount that actually spins (like the entire heat sink rotates if you push on it) when its fully fastened down and a single junky sleeve bearing fan. The included thermal paste is garbage. The mounting bracket is also a piece of shit.
$50 for a PHTC12DX gives you a cooler with higher quality fins, tubes, thermal plate, and mounting bracket, and two of the best 120mm pwm hydro bearing fans plus a huge tube of the same exact paste that noctua uses. It also looks a lot better and comes in a million different colors.
The cost ends up the same after you buy two good fans and a tube of thermal paste. Which do you want?
From what I have heard, the Phanteks and Noctua products are both made by the EXACT same OEM company. The thermal paste is definitely the exact same.
Don't get me wrong, I have built three machines with CM212, but after going with a Phanteks I am not going back to the CM212. The cost ends up the same and you get a substandard product. The only thing that sucks about the Phanteks is the metal clip + plastic things suck. Instead, bend the metal clip out a tiny bit and use a regular fan screw. This is self explanatory/obvious once you get to this step, trust me.
Also, my Phanteks is giving me better cooling than my H100i and its inaudible. You cannot get better air cooling beyond that $50-70 price point, everything else is just hype. We are talking a 2-5 degree C difference between the two fan tower coolers (Coolermaster 212) and the air cooled three fan tower heatsink coolers like the Thermalright SilverArrow SB-E, Noctua NHD14, and Phanteks PHTC14DX, or the H100i/H80i if you run the exact same fans on all of these products.
The three fan heatsinks look awesome, perform awesome (but maybe 5*C AT BEST over a 2 fan tower), but block ram and take up a lot of space inside the case.
The H80i and H100i have pump grind issues when the motherboard is at certain orientations. They also can have cavitation problems when your power supply varies slightly on the 12v rail. Additionally, you add two fans or four fans (80 vs 100) for push pull and your making a lot of noise. The risk of leakage, while slight, is present always. The mechanical nature of a pump can fail as well.
If you want anything better than that 2 degree C difference you need to pay about $350 for watercooling.
I say this above sentence with the assumption that you have proper air flow dynamics in the case (positive air pressure) and good cable management so that heat is not trapped in any zones.
