I have ordered from both and love both of them! Don't know about the Bottom Line/So Fine but funny story--many long years ago when I first started quilting, I would faithfully iron my seams and they would fall apart! Back then I didn't know the difference between poly and cotton thread. I thought my iron was overheating and became afraid to use it so I cut off the cord so no one else would fish it out of the trash and use the "defective" iron!