Fuji Flex is "Crystal Archive" as well, as the "Fuji Crystal Archive" trademark is a marketing term about the emulsion technology, while the other terms are about the paper/surface's it's used on. When you say you may choose Fuji Crystal Archive ... that's really not "paper". Just like Kodak uses the term "Endura" (also a marketing term chosen to imply longevity), "crystal archive" is sort of marketing speak for the silver halide technology. There are about 10 fuji crystal Archive papers, the two most popular with landscape photographers is "flex" which is basically not a paper but a plastic base, and results in an ultra white paper with an amazingly smooth and high gloss surface, and "Pearl" which uses some type of encapsulated Mica technology which is somewhat similar to the iridescent look of a pearl - probably created for reasons similar to Kodaks Endura Metallic paper. Both produce beautiful prints with characteristics that cannot be duplicated with inkjet papers (some things are close, but especially flex ... nothing looks like flex it's truly amazing) You can also get a more traditional luster surface (which has basically evolved from the "E" surface standard of Kodak papers), gloss, etc.
The Chromira (I have one) produces great chromogenic output, has great color management features to ensure the highest quality for good operators. Some print mounting techniques (such as face mounting) is very hard to do (especially with inkjet output) and fuji flex makes it easier. A great many well known landscape photographers use flex, in the U. S. both Peter Lik and Rodney Lough specialize in very large prints on flex that are then normally face mounted to lexan or acrylic and then mounted onto another sheet of that or dibond to make them really flat yet not as fragile as glass.
While many of these photographers brag about the "Crystal Archive" technology (reminds me of the Superman movie where he goes to the crystal palace and there all the knowledge of his former world is contained in some crystals), there is no magic, and bottom line the "crystals" are all removed during processing, leaving only the dyes that were coupled to them. And while these prints can last a long time and look great (and I personally print some things on them) don't be deceived by the "Crystal Archive" term. While certainly a huge advance in longevity when they were introduced a couple of decades ago, their resistance to fading is now far less than most pigment inkjet technologies - and not in an insignificant way. In fact I believe Rodney Lough sells a "poster" type print that "isn't" archival like his "normal" prints - that he prints on an Epson printer with Epson inks ... funny because in reality that print if treated correctly and displayed/stored under identical conditions would outlast the Fuji prints by a very long time.
The main appeal to chromogenic now lies in it's price .. it is much less expensive (except for flex which costs 4 times more than the other crystal archive papers) and far more automated than any current inkjet technology. At some point in the future that will probably change, although that change is certainly happening far slower than most thought it would 5 or 6 years ago. (maybe that's why Kodak is selling their photo paper and photo paper printing business because while they make them money now they know they aren't the future).
One last thing of interest, while inkjet printer gamuts exceed what can be done with silver halide printing, the end results are not remarkably different visually, and often the inkjet prints appear less saturated and less colorful because of the nature of the dyes used - to many, (especially consumers buying the photographs) they look as good or even better.Where inkjet dyes are sort of opaque sitting on top of the paper, these papers dyes work differently allowing the the paper itself to have more influence in the final image. I haven't found a "metallic" inkjet paper yet that comes close to Kodak metallic for images ... perhaps somewhat close if they are high key and lighter toned, but not mid or darker toned. Just a difference in the way the dyes work between the two technologies.