sFlow and NetFlow data collection and monitoring

I'm looking into network monitoring utilities for both gathering basic statistics conducive to my enterprise as well as looking for anomalies in traffic traffic. I'm curious as to how NANOG approaches this problem.

Are most of your statistics gathered via netflow, or sFlow? How do you gather them, and process them? What do most of you use the data for? Deciding (de)peering agreements? Reducing latency to your biggest customers?

How 'standard' are the industry standards (Fluke, Arbour). I've experimented with pm-acct, and flow-tools. How do you leverage flow-tools and pmacct?