I had a fellow GJ'r PM me with a couple questions. We exchanged replies and we agreed it might be benefitial to include it in the thread, so here it is. The questions concerned who I consider is the top level for Japanese tool quality, ie. Ko-ken, KTC, Nepros, etc and thoughts on ANEX tools:
I'd place KTC's Nepros line at the top. With form factor and surface finish preferences put aside, and strictly speaking of the utility and durability of the tools themselves, I have no doubt that they are top-tier. The manufacturing takes place in the same plant between both KTC and Nepros brands, but the manufacturing processes between the two are quite different through it's various production stages. Even the base material, the tool-steel stock that is used on Nepros' socketry stuff is different from the regular KTC line. If you include final product packaging into the "quality" equation, then Nepros probably takes the spot for the most over-spec'd hand tool manufacturer in the world.
When you think globally, Nepros' product lineup isn't too large however, so perhaps that does limit their placement on the podium, when compared with some other top-tier manufacturers of the world.
Ranking of Ko-ken, KTC, TONE....the big three of Japan.
From the perspective of supplying the various industries/trades, I'd place KTC and TONE above Ko-ken. KTC/TONE quite simply offers a more well-rounded range of tools, making them more of a one-stop shopping experience. I like to place KTC above TONE for the fact that TONE imports a lot more tools compared to KTC. In addition, unlike KTC, TONE isn't forthcoming when it comes to product COO. KTC is transparent with where their tools come from, and I applaud that. Of course, this isn't a concern for many out there, so that's a subjective matter.
Having said that, they are competitors, so they each offer things that the other doesn't have. In general, KTC is a lot more geared toward the automotive industry, while TONE is geared toward the heavy industries.
As you may already be aware, Ko-ken is very much a specialist in socketry items. Their target market isn't as broad as KTC/TONE. The vast majority of their products are made in-house though, so that makes them a rather special manufacturer (to me at least), and I like supporting such small companies. It's an easy choice for me to support them because they have continually met or exceeded my expectations over the course of a dozen years. I know what to expect as they manufacture with little to no production/dimensional variances....meaning you can pretty much expect to see a product replacement that matches what you had bought years ago, with little to no changes to dimension/appearances (this attribute isn't necessarily an industry norm).
Regarding ANEX tools, I have a handful of things from them and for the most part, they are good.
I haven't had any issues with their stubby 1/4" bits and various power bits over the years (cross-recess, Torx, In-hex (both standard and ball types).
I had a 1/4 flex bit shaft that lasted about 6 years of hard use.
I have a couple of their impact-ready 1/4 flex shafts and they seem alright (the bit locking sleeve is a bit cheapy I admit).
Got their smaller inter-changeable head craft hammer which is great for around-the-home stuff.
I like their Mag-catches as well...very handy.
Their ultra low-profile + / - wrenches have saved me a lot of grief on a couple occasions.
Got a small assortment of their trim clip removers which I've been quite happy with.
I got a couple of their bit ratchets (Taiwanse made) and although the backdrag was a little high (prior to me modifying the spring), for their small size, they have surprised me with the torque they can handle.
The only thing I cared very little for was a set of their 1/4 nut runners/box bits. Looks like something from the bargain bin aisle. Nothing special on those.
All in all though, ANEX tools have served me quite good.
Part of me doesn't want to believe what I'm seeing. A rather blatant copy it seems, of Knipex grips, by a (now defunct) Japanese manufacturer. I want to believe they are cheap Chinese knockoffs, using Aigo branding and Knipex features to sell to unsuspecting buyers. 
