I only run 3mm filament of which around 50 percent of which came from Makerbot, and have from the start with the cupcake, then the tom http://www.thingiverse.com/thing:7063 , and then the reprap http://www.thingiverse.com/thing:8957 , and then the ultimaker gen4 and mk6 mashup http://www.thingiverse.com/thing:10380 (when talking ABS), and for PLA, mostly the original Ultimaker http://www.thingiverse.com/thing:10802 .
It is high quality if not priced a bit high IMHO. Consistent yes!!! I have yet to see filament from anyone that is 3mm exactly ever in the over 150lbs in the last 2 years. It varies from 2.75 to about 2.98 depending on who I got it from and which roll but is very consistent across the roll.
Personally, I buy most of my filament from Ultimachine in 5 pound spools. Both ABS and PLA. I have some I bought from Makergear and then tons of the spools from Makerbot so I spread it around. I've yet to have a bad roll in 150lbs 347lbs (just did inventory and reciepts) of filament if that says something.
Cost per pound, Ultimachine beats them nearly 2-1. Makerbot is very high quality and nice colors, but you pay for it and then the spools are only 2.2lbs (1KG). Again, I look at it as cost per lb as my key choice but sometimes I end up with Makerbot since they have good colors and I know it's high quality. In fact, looking at prices, my filament pile at home is worth double what I paid for it. Todays prices, I might have $1K in filament??????
I too have an Ultimaker and have been down the jam syndrome. Fore some reason, natural PLA seemed to be the one that jams the most. Being that I got it from all 3 places and they all act the same I say it's not brand based. Truth is, I replaced the nozzle and brass tubes and even the PEEK insulator with parts from Makergear since they match up to the existing Ultimaker heater and reduced my problems. Also, for me, the silver PLA works the best hands down. I don't know why, but it just prints and prints and I got it from Makergear.
Again, I have several bots but always use a MK6 extruder for ABS, and then the only one I use for PLA is the Ultimaker.
Unless you have a heated bed, ABS doesn't work with the Ultimaker. Further, no way can you get the extrusion feed rates with ABS (in other words, maybe 40-45mms before you jam). ABS just doesn't flow as fast.
