Hypersphere

The 60% keyboard is my favorite form factor. I have owned the following 60% keyboards: HHKB Pro 2, HHKB Pro 2 Type-S, KBP V60 Matias Click, KBP Matias Quiet Click, Poker II, and Tex Beetle. The HHKB (both standard and Type-S) have the best default layout and keycaps, and I like the Topre switches. The Tex Beetle is well made, but it has an usual staggering and 1x Backspace and Right Shift, which I find too small. The Poker II has a standard layout and it is easy to find replacement keycaps; however, I like to remap my keyboards to a Mac/HHKB layout, and the Poker II does not permit remapping the Fn and Pn keys, so I end up with two dead keys. The KBP Matias switch keyboards are superb; you can swap Fn with Menu, which has a scan code so that it can be remapped without leaving any dead keys. Moreover, the Matias switches provide the best tactile and/or aural feedback of any switch I have ever used, and the force-displacement curve feels just right. I like the Matias switches better than any Cherry mx switch I have tried, and this includes blue, green, red, black, brown, and clear. Replacement keycaps are an issue, but I have been able to find Alps/Matias keycaps by harvesting them from vintage Alps keyboards. For me, the best 60% keyboard is the HHKB Pro 2, either the standard or Type-S. It already has the layout and keycaps I prefer, so I don't need to do anything else to the keyboard except to use it. Next best in my estimation is the KBP V60 Matias keyboard. I have a slight preference for the Matias Click version, but if you want a really quiet mechanical keyboard, the Matias Quiet Click is the quietest mechanical keyboard I have tried -- perhaps even quieter than the Type-S HHKB Pro 2.

I should preface this by saying that I have tried many keyboards with various form factors, layouts, switch types, and keycap types. My all-time favorite switches are Topre 55g and IBM capacitive buckling spring (Model F). My next favorite switches are various Alps (including Matias) and NMB Hi-Tek "space invaders" (black or white). My least favorite are Cherry mx. Within the Cherry mx keyboards, I have owned CM QF Stealth mx green, Ducky Shine II TKL mx brown, Filco MJ2 TKL Ninja mx blue, KC 84 mx blue, Kul ES-87 mx clear, Kul ES-87 mx red, Poker II mx blue, and WASD V2 87 barebones mx brown. These were all reasonably good keyboards within the Cherry mx variety. Regarding the two you are considering, the Filco has a great longstanding reputation and Kul has rapidly established a good reputation as a new company. Filco has a nondetachable cable, whereas the Kul has a detachable mini-USB cable. Filco uses Costar-type (wire) stabilizers, while Kul uses Cherry stabilizers. I prefer the Costar type, because they feel less mushy than the Cherry stabilizers, but some people prefer Cherry stabilizers because it is easier to change keycaps on stabilized keys that have Cherry stabilizers. I think that both Filco and Kul use a dual-layer PCB and both have plate-mounted switches. Filco has its LED lock indicators in the case, while Kul uses LEDs under the corresponding keycaps; I prefer the LEDs in the case, because then I don't need windowed replacement keycaps (I almost always replace the stock ABS keycaps with dye-sublimated PBT keycaps for their better appearance and dry slightly textured feel). The Filco has no DIP switches; the Kul has 8 for various settings. Both keyboards have a Menu key that can be remapped in software to your own Fn key, a feature that I really like. I have recently sold my Filco and both Kul keyboards, but if I were to buy one of these again, I would go with the Filco for the overall fit and finish and the Costar-type stabilizers. My most recent Cherry mx keyboard is a WASD Keyboards V2 87 "Barebones" (no keycaps) with mx brown switches. I am typing on it now, with a set of Imsto dye-sub PBT keycaps. I like the Costar-type stabilizers. In addition, it has red pinhole LED lock indicators in the case, and 6 DIP switches with various useful settings including Fn/Menu swap so that I can make my own Fn key in software. The WASD barebones is $95 for the base model with no extra charge for either blue or black switches; mine was $100 with the mx brown switches, but you will need to add your own keycaps. If you go with WASD keycaps, you can use their online customizer to design your own layout. I like the WASD as much or more than any Cherry mx keyboard I have owned or tried, but my favorites are still the HHKB Pro 2, RF 87ub 55g, IBM Model F XT, and IBM Model M SSK.