I'm your bandwidth man
Quality bandwidth : Internap ( < 50ms responses worldwide) fastest fucking network you can be on. They basically route your traffic through the fastest provider. Expensive.
C&W (Exodus) Great peering, big network. Basically all tier 1 providers are quality bandwidth (Verio, Level3, Williams)
Low quality bandwidth: Cogent (shitty routing - your packet travels the freaking country before it can get to the destination, bad peering, company's financial decision and situations or doubtful), Yipes sucks too.
Basically some hosts offer BGP routing meaning that your network is multihomed so customers can get to your sites via more providers. It's a network load balancers. This means redundancy for you BUT some cheapo hosts have a cogent/level3 BGP setup but route 90% of traffic through Cogent and if it goes down level3 kicks in. Still shit bandwidth.
If you want top notch bandwidth I can give you jaw dropping prices (on a 9Gbps network) for Internap, C&W and Williams for pull traffic.