For PLA and PETG, I like MatterHacker, though I have been buying some Voxel PLA lately and that's been pretty good stuff too. Voxel does run sales that get the price down to $15/$16US a kilo.
For ABS/ASA, I'm still using a the same kilo of Zyltech ABS I bought 5 or 6 years ago. And I still haven't used 200g yet. I did dig it out this weekend to print a couple dozen custom cable clips for my boat with it though.