I choose the ones that are free. Most of my brass is range pick up. I watch for the mall ninjas to come with cases of new ammo. They blast away, and leave huge piles of once fired brass. Most times they leave the boxes, and the bag with the receipt from the store they bought it at as well.
Oh and as of late I have seen lots of LCC head stamps on Federal Ammo. Also all seem to be staked, or crimped in place. A few seconds with a Lyman tool then they are good to go.