FWIW, I’d prefer a “product type” breakdown, but one with a little more granularity. However, that detail depends on the nature of the product category.
For instance, with kits, I’d like to see everything broken down by genera (aircraft, armor, civil automotive, nautical, etc.) and figures (injection molded sets, resin, 3D printed, white metal) broken out from full kits and injection molded accessory sets (and possibly break full kits down between injection molded and “other” - like resin and 3D printed). Scales should be grouped together, so that, say all 1/35 scale figures are grouped together and separate from, say, 1/72 scale figures, even if the subjects, nationalities or periods are the same. The same for full kits and accessory kits.
I’d like to see accessories broken down into PE, resin, 3D printed, diorama supplies (ground work, bases, texture materials - scatters, static grass, laser cut paper plants, snow and water effects, etc.), wheels and tracks, turned and resin gun barrels, decals (to include stencils and masking sets), etc.
Supplies could be included with paint & finish or broken out into paints (and finishing products, such as washes, filters, pigments, etc.) and construction materials (glues, putties, fillers, styrene stocks, RTV and resin casting, etc.).
Tools should be its own group, possibly broken down by hand tools, measuring tools, power tools (hand held, desk top, battery powered, AC powered), and special fabricating tools (punches and dies, PE bending breaks, jigs, forms, assembly stands, etc.).
Books and reference materials should be its own category, broken down by subject, then nationality, then historical period.
When I’m looking for a kit, I’ll search by the subject and scale first. Injection molded and resin second.
When searching for AM accessories, I search separately for PE, resin and wheels or tracks for particular subjects and scales. So, for instance, I’ll search for 1/35 scale T-32 tracks and gun barrels rather than look for a list of AM tracks and then scroll through it looking for some set that will fit the subject I’m building.
When searching for figures, I search by subject (usually determined by nationality and historical period) and scale. So, 1/35 scale British WWII infantry figure would be how I’d search for either injection molded sets or individual resin, 3D or white metal figures that just happen to be that.
When searching for paints and other finishing materials, I search by type of medium (acrylics, enamels, oils, dry pigments, acrylic gels, etc.). If I want dry pigments, I’d rather search for just those than have to look through a long list of all kinds of weathering products just to find sand yellow dry pigments or a pigment fixer.
When searching for tools, I search for the kind of job that will be performed - cutting, sawing, filing, grinding, drilling, holding, soldering, bending, gripping, folding, etc. I then look for the type of tool - hand tools, power tools, etc. If I need a hex punch and die set, I want to search for “punch and die” sets.
When searching for diorama materials and supplies, I search for the media - ground work materials, basing materials, texture material - or the effect I want to create - snow, ice, water, vegetation (grasses, bushes, trees, cactus, dead fall, leaves, etc.).
It’s more important to me that I can find what I’m searching for more than how things are broken down and categorized in the Review Listings, themselves. I just don’t want to have to spend a lot of time scrolling down through long, long lists of reviews to find the one review of some particular kit of a particular subject in a particular scale. The same for AM accessories.
I mean, what constitutes a “new kit” and why would I want to search through a dozen T-72 tank kits to find a Sherman? And then, who would decide that the Sherman kit from RFM that I’m looking for a review of is no longer a “new kit” and when that review should be moved to the “old kit” listing?
Era is also fraught with possible issues. When does a T-34 used in Bosnia become a WWII subject? Suppose its of the post-war Czech manufactured type that never saw service in WWII? What happens to the neophyte modeler who doesn’t know that T-34’s were manufactured after WWII in countries other than the Soviet Union? On the other hand, a 1/35 scale T-34 is exactly that regardless of the era or place it was made or employed in or whether or not the kit was made in the last six months, the least six years or the last six decades, new manufactured, re-released, or bought from an estate sale in an old, yellowed box.
Anyways, just my .02 hundredths of whatever currency, old, new, or nationality you’d like… LOL!