I have found the key to successful noise reduction is sample size: very small is best.
Sony Noise Reduction software does a very good job in most cases. I'm not at my editing computer at the moment, but I believe Noise Reduction is a Sony plug-in.
Background noise reduction is not an easy problem. that is why sound folks go to great extent to eliminate noise in the environment that filming occurs in. Most if not all "noise reduction" software will leave artifacts because you are removing frequency content of all signals.. These artifacts' observability is proportional to the amount of reduction you do. Artful noise reduction is a little bit of this and a very little bit of that. There is some hope with more surgical methods like spectral manipulation (SpectraLayers), but that takes a high degree of skill and time in any case. If you find the plug that eliminates noise without reducing audio quality of the desired signal.... let me know. There are some good vids on the web that cover doing artful noise reduction using standard tools that most DAWs have including Vegas Pro.