I have tried thermaltake and I personally wound't try them again. I'm sure you can make them perform as well as Noctua's, but I bet that the noise level will be much higher. I usually go for the proven-through-rigorous-test performance/silence, for which Noctua and Scythe are very safe and time-proven bets, but if you want to take chances or experiment, go ahead. It might payoff or you might end up wanting to buy new one's. It's just that once you hear a good Scythe or Noctua, you truly know what silent means
You can likely find a few other brands just as good, but I just go where the objective tests are, not subjective opinions from people that probably have a not so silent system anyway so that they think their fans have a good performance/noise ratio. Not that everyone is like this, but this has been the majority of my experience with this.
I mostly used this place as guidance: http://www.silentpcreview.com/section12.html