Only wa. Nothing remotely inexpensive, making a knife that thin is very difficult and involves a lot of failures -- which you pay for when you buy a successful effort.
Best deals in laser gyutos are the Konosuke White carbon and Konosuke stainless. Put up your umbrella, it's about to rain carbon info.
The carbon is very nice; the particular alloy, Hitachi Shiroko (aka White #2, aka Shirogami #2), hardened to 63ish; it's too hard to true on a steel, but otherwise fairly easy to maintain as carbon goes; you don't have to let it grow a dark patina -- I have 70 year old carbon Sabatiers which glow like a well-maintained tool. It's just a matter of periodic scouring baking soda.
Except for the alloy, the stainless is the same knife as the carbon (and so is the very expensive HD, for that matter). The alloy is Hitachi G3, hardened to around 58, which is a little on the soft side for some people (not me). Considering that it's a laser, it's actually pretty durable. You can true on a steel if you're very careful; so "net-net," as a friend of mine says, it doesn't have to go to the stones more often than the other Konosukes. Perhaps the most practical of all the lasers.
Sakai Yusuke used to be the bargain laser, but I don't know were to get it anymore. Off the top of my head, the other quality lasers are the Tadatsunas in both white and stainless, the Suisun Inox Honyaki, and I think the Gesshin wa either qualifies or almost does as well... but you'd have to call Japanese Knife Imports and ask. The Tadatsunas are even thinner (but not by much) than the Konosukes.
If you're thinking wa, and are willing to spend the bucks, it's hard to beat the Masamoto KS (again, carbon) gyuto. The Masamoto is about as thin as you can get, and still be "regular," plus it's a Masamoto. In my opinion it has a very strong claim on "best knife in the world at any price."
FWIW, which is damn little, I have three Konosukes, an HD 27cm gyuto, an HD 30cm suji, and a stainless 15cm petty. Very impressive knives, which suit me to a "T."
Everything considered, if you want a laser, the Konosuke stainless could be a good choice. But fun as XTreme thinness is, it puts a heavy premium on skills. Jut just listening to your druthers, I'd lean towards the yo-Tad, yo-Gesshin (perhaps the wa-Gesshin if it's not too thin) and the Kikuichi TKC as list toppers. Re the Gesshins, Jon, the guy who owns JKI, has very similar tastes to mine in terms of profile, he's very high on them, and for the time being I'm taking his opinion on faith.
Edited by boar_d_laze - 9/6/11 at 12:46pm