best is rather subjective for both. all we can really do is point out the most popular and our personal favorites
like he said the "big three" are kershaw benchmade and spyderco...
benchmade and spyderco have similar price points, both offering lower dollar knives but alot of higher dollar knives as well
kershaw is praised as a bargain company offering a great product at a lower price, but also offering those higher dollar knives as well especially with the ZeroTolerance knives they put out
also in the lower dollar bracket would be your buck folders [who also have great higher end knives such as the buck mayo tnt etc] crkt, as well as cold steel.
and in the higher end of the spectrum you makers like lionsteel who's emerged with a great knife the sr-1, Chrise Reeve's legendary line up, Rick Hinderer's unattainable grail knives, and your custom folders too.
as for steel you've got your super hard zdp-189, s90v and s110v, your very popular s30v which is praised as a great all around steel. your tool steels d2 and m4, your higher carbon stainlesses like the previously mentioned s series but also including 154cm and vg10. and last but not least the carbon steels such as 52100, 1095, and a whole list of others!
i know i'm missing a bunch but it gives ya an idea of whats out there. throw a price and these boys can have ya hooked on knives in about 6 clicks. buggers got me too
