IMO the ZT Hinderers are as tough as a knife in that class gets, and other than buying an actual XM-18, it is going to be hard to find something tougher.
ZT has really picked up KAI's high-end items and ZTs are best compared to older Kershaws like the Spec Bump, Titanium/ZDP-189 Cyclone, and Composite Tyrade in terms of quality that pushes the boundaries of production knives. They are tough as nails, their quality is very consistent, the finish is exceptional, and they are probably going to give the best longevity of any knife in their respective category.
When it comes to steels used, ZT is probably one of the most consistent companies in using fantastic steels on all of their knives across the board. KAI-ZT is also using CPM-S35VN and ELMAX extensively, which for folding knives are very tough steels to match because they give super steel-level performance in every single category. In my personal opinion, I think they are two of the best and possibly the best steels for such application. ZT also uses CPM-154 and CPM-S30V, and KAI is very competent in their heat treatments of all of these steels. Recently, ZT has also started using more M390 and other super steels. On special knives, they have also used CPM-3V and CPM-110V composite. They don't mess around when it comes to choosing the best steels for the job...
ZT has also really pushed the boundaries when it comes to pivot, joint, and bearing systems. They are designing these parts not just with strength in mind, but longevity in a sense that these are friction parts that will see the same repetitive movement and they are designing them to reduce wear and account for long-term wear patterns. Like the Sebenza, I dare say that in 30 years from now that ZT frame locks used every day will still not develop blade play thanks to their designs and lock up within acceptable spec. Their machining of G10 and titanium alloy is also notable.
But, the ability to withstand the next 5 world wars does come at a toll: they are generally pretty heavy and bulky, which some love and some hate. If you like thin, the ZT0566 gets thinner than other ZTs, but it still is what I would call anywhere near 710 compact. ZT revised many of their pocket clips and the newer designs I think do a better job in carrying the larger folders comfortably. Additionally, their blades are great but they do tend to favor heavier work than they do lighter work in which precision is most important. With the added weight, this can make some cutting more challenging versus a knife without such a beefy build. The 0566, 0770, 0801, and the newer Hinderer models seem to be addressing some of these issues and expanding the versatility of the line.
