Direct Scan,,, bar none!!! It refreshes at 18 frames per second, as opposed to the typical 10 fps of others. But,,, yes,,, you must have a laptop to run it, so it may not be as convenient as the smaller ScanMaster setup. However, it will work on laptops of 286 and up, so you can usually find those for next to nothing...
I actually know the guy who designed this software, and he is one smart cookie...!