Look through Chef Knives To Go; the best ones aren't 'brands', they're made by individual craftsmen.

Honestly, the best ones I have are from knife shops I’ve gone to while visiting Tokyo (thought I had some pics of the shops or the knives, but evidently I do not), as well as one from an old-school Japanese blacksmith in the Narita area that uses traditional sword making techniques:

That said, if you’re in the states, the best well-known importer I’m aware of is Korin. If you’re near NYC, their shop is downtown near the financial district. They periodically have sales where you can snap one up at a reasonable price.

Yes, they are a good bit more pricey than your bog-standard cooking knives, but they are truly a delight to use. And some of the more specialized types (like the aforementioned nakiri; or a boning knife (honesuki), which I’ve used to break down whole poultry and bigger bone-in cuts that I want the bone out of) are kind of a blast. No, you don’t need them, but if you’re into this sort of thing and really enjoy cooking, they’re a very fun and a delightful addition to your cooking process.

Material: stainless will hold its edge better, but is more of a pain to sharpen, though tends to be more difficult to get a truly insane edge on. Carbon steel is far more finicky in terms of care, but you can get that wicked sharp edge much more easily, and they’re not hard to re-sharpen.

If you go for carbon steel over stainless, do not neglect caring for your knife. If you want to get a good baseline for very good knife care, look at what a sushi chef at a nice sushi place is doing when they are slicing their fish. The actual technique (slicing the fish) is admittedly somewhat specialized to sashimi and nigiri prep, but the way they keep a damp cloth to the side to immediately wipe the blade after use is what I am talking about. And, above all: never, ever, ever put it away wet or damp - that’s a sure way to rust your blade. Ideally, put a dab or two of oil on a paper towel and rub the metal down with that for a protective layer (I use tsubaki oil).

Do not use a sharpening steel, or those crappy v-slot sharpeners, or roller-sharpeners, or things that rely on ceramic or metalloceramic rods - you will immediately fuck up your blade. Invest in a decent whetstone (yes, really - if you do it a lot, get multiple grades of whetstone, as well as a stone fixer), and learn the technique appropriately (this includes understanding handed bevels, as well as getting a literal feel for how the knife edge is ground when you are sharpening it).

You should never weld a knife. It will ruin the hardening and temper. Just re-profiling the existing steel is a much better idea.