The 21 is the "crème de la crème" of releases for what it's worth in my small collection. I don't own a regular, but the 21 has the easiest release out of my early Umnum, and my 25. Those blades require a little more concentration and effort to release, while the 21 is a "no-brainer". It's kinda weird but the 21 in general is growing on me again. Maybe it is not the most popular in concept, or the most sought after of the CRK family, but I gotta say, I think there was some serious thought and inspiration that went into the design of 21. Like maybe is was the last large folder where Chris was trying to make a knife that was functionally perfect, rather than just new and different, or more appealing, if that makes any sense. I dunno, until I handle a regular, I suppose I can only guess, but I suspect I'm onto something with my love of these 'pedestrian' 21's.