Posting Freak
It’s always so subjective what is the “best” anything. Some will want the latest, others the very first original and still others something in between. Also when you say “date code” or “serial number “ they’re practically the same thing. A way of linking the razor to manufacturing data. I guess if you’re a maker/vendor you determine if there’s a sufficient market for an item or a process like serial numbers and go with that.