How does bandwidth quality differs?
Rackspace told me that their bandwidth is better thn of those cheaper hosts.
What factors should a consumer look at when chosing a host?

Rackspace is on crack if they say their bandwidth is better than others....

Bandwith quality all depends on how close you are to a loop and to a peer. You could have cogent / yipes bandwidth and be right next to a peer and have better quality bandwidth that verio, at times.

However there are a few company providers that have received a good reputation as quality providers. I would have to say that National/International wise Verio, Level3, Internap, Global Crossing, AOL Time Warner have proven to be quality providers.

When chosing a dedicated server location, you want to check for mulit-homed capabilities (more than one provider), the actual providers they use and how close their peer is, the amount of bandwidth those lines carry.

Currently I use Hurrican Electric, Yipes, Pajo as my providers on my machines. Mainly because HE (hurricane electric) has a backbone coming from dallas to detroit ( i live 1 hour from detroit) so i get a nice smooth connection. Yipes because it is rather inexpensive and covers a good majority of the southeast part of the US, and Pajo because it goes from dallas up the california coast into canada.

I would like to get a machine in NewJersey with Internap and AOL bandwidth... so i can support the midwest and eastern canada a bit better.

That not true what rackshack said. NAC is good bandwidth

I think you mean RackSpace but I agree with Jonathan in terms of Bandwidth quality