I´ve read a bunch of stuff about this matter but nothing like hearing from the users them selves.
Which noise removal software obtains the best results? Speed is also a factor, but quality is the main thing.
You'll probably get as many answers as there are programmes. The notion of 'best results' is also tricky since it depends on how else you process your images and what you do with them by way of display or printing afterwards. For screen display and for anything other than really large prints I suspect you won't see much difference from using any reputable programme.
I used Neat Image for a long time which is very good and I also occasionally used NIK Dfine - the one advantage of this programme (and a few others) that it allows selective NR to be applied to different parts of the image.
Now though I use the NR tools in Lightroom. I haven't seen any stand alone programme that does a better job. While it doesn't have the same kind of options for selective reduction as some do it does have sliders labelled 'detail' for both luminance and color noise which do the same thing - only the decision about the levels of NR applied to different parts of the image is decided by the programme. Since LR moved from version 2 to version 3 I haven't used anything else.