I'm using S25FL127SABBHIC00 chips for my Artix boards which I bought a while ago for cheap. These were the cheapest 1.0 mm BGAs I was able to find (that would actually be useful for me), so I used them to practice reflowing BGAs and tuning reflow process before I started using them for a real projects. What I liked of them is that despite BGA package they can be very easily broken out on a regular 2 layer board. But it looks like these parts are not stocked anymore by Mouser nor Digikey, so once I run out of them, I will have to look for something else, perhaps in even smaller 4x4 mm USON package to save board space.