I have both the B+W 103 (3-stop) and the 110 (10-stop) that you linked. For most moving water shots, light trails at night, etc., the 3-stop is sufficient. I also sometimes stack aB+W KäsemannCPL (Slim mount) on the 3-stop for a total of ~4.75 stops plus the ability to cut reflections (great for waterfalls). The 10-stop allows some nice creativity with very long daytime exposures. Great for moving clouds, for example, or to blur out moving people near a popular architectural feature. Do keep in mind that for the 10-stop you'll need a good tripod, you'll need to set the focus before putting on the filter, and you'll need to set exposure manually.