I've just been through the same quest. My own conclusions are :
- ISP Decimator (or Decimator G String if you need a loop) is supposed to be the high quality standard, but far from cheap even second hand (100+ euros for the cheapest in France).
- Boss Noise Suppressor (NS-2) or Electro-Harmonix Silencer are easy to find second hand for around 50 euros (French prices) and good enough for most people apparently. And they both provide a loop configuration.
They are definitely far better than the Berringer and other 20+ euros pedals.
I bought a Silencer. From my first few tests, it's easy to setup and will clean most hiss and feedback from a few distortion and overdrive pedals, or from a noisy guitar (I have a piezzo cigarbox that really needs it). Only important point one might not know going in is, it really does not play nice with the use of the volume on the guitar (you will fall under the threshold as sound as you lower the volume going in), so I advise a volume pedal after your effect loop and noise reducer if your need any control on your output while playing.