I find http://www.nzbsrus.com/ is the best, I don't always like binsearch.info, and NZBMatrix would be good if I could be bothered to pay to get more than 20 days retention.
Newzxxx
Not sure why it hasn't been posted already, but I find www.nzbindex.nl to be far superior to the other indexing sites.
My main issue with NZBMatrix is that they lack a decent way to select multiple things. You have to download each thing as its own NZB (although they did use to have a queue thing set up to allow grouping up to 10 files into a single NZB, but this has been removed). Where as binsearch.info I can browse for something and just click a tick box on as many results as I want and get a NZB file containing everything I selected.