I use wooden trays that came from cigar boxes. The tray is flat, has sharp corners, and makes it as easy as falling off of a log to count afterwards. dump the unsorted brass into a pan or other flat container. grab it by the handful, sort out the large ones, pour the small ones into the tray. it takes little effort to line them all up with base down. sorting 40 from 45 is ridiculously easy, and working on your 9 and 380 brass is as simple as going over the tray visually and pulling the short ones out of the stacked 9 brass with any tool that you have handy. I've even used a pen that tapers conveniently enough to grip the .380 mouth and then shake off into another box.
The box works so well for me because it confines them absolutely into a block, doesn't allow them to tip over, and the corners and edges are completely square.