There are only 2 places I order from:
http://www.makergeeks.com
http://www.orbpolymer.com
I order alot more from MakerGeeks.
MG has the higher quality material (though not by much).
MG does free shipping on any order in US, Orb ya have to buy 3 rolls to get free shipping.
Orb only carries ABS, PLA, and PETG, whereas MG carries a huge range of specialty filaments as well.
MG runs spools of as they are ordered directly onto the spools that are shipped to you. Orb used huge warehouse spools and cuts orders off of there. The end result is ya get firmer and fresher material from MG....esp so on less popular colors. The drawback is that it can take a day or 2 for MG to ship your order, where as with Orb it goes out that day or the next (depending on how late in the day ya order).