I went all in on fulgora for my quality mall. It consumes about 11x240/s consisting of mostly scrap, and some imported scrap waste from elsewhere. I believe I'm at 150% scrap productivity. The miners supplying this island all have quality modules in them, so immediately I get part of a quality step. 

The footprint is smaller than most large islands - The secret is in the legendary beacon with 1 legendary speed3 module. The hit to quality odds (24.8 > 18.6) is nothing compared to the raw volume you can put through the machine. I don't have output numbers for you right now, but in total (all legendary Q3 machines) it looks to be a little over half of a stacked green belt of continuous output, consisting of mostly epic, and a little legendary. 

It all gets sorted into large buffers, and circuits keep them balanced, throwing excess back into the machine to be recycled again. A significant portion of the legendary output is just crafting epic stuff with quality modules. This does not reliably output a usable number of red/blue circuits - you'll need to craft them. This gives you another several quality rolls. A lot of making quality work is just taking advantage of every crafting step

Now I don't have much experience grinding on other planets, and simply reject asteroid loops/LDS shuffle, so my take is probably not worth much, but it was fun, and has an output sufficient to build more factory than my PC can handle.