I would recommend the Naniwa 12k. I have used the C12k and really like the edges, but I don't recommend it anymore. It's just so slow. If you are a new guy, this leaves more room for a bad stroke to slip in and ruin your edge. If you have a bunch of razors, the extra time you'll spend on this compared to a Naniwa or similar could start to become an issue. But here I am showing my own personal preferences, as they are moving from quality only to quality and efficiency. I like the edges off a C12k, but I prefer to get there faster these days.