You want both. Card scraper is way more versatile but unless
you are part gorilla, your thumbs will get tired long before
you’re done scraping.
Card scrapers are sold in different thicknesses and believe me
you want to have some choices. The thick ones are great
but you’ll get tired faster.
The card scraper holders are alright but they slow you down
a lot. The cutting geometry on a card scraper is different
from a #80 and the burrs get dull faster in the center
where all the action is. When you hold it with your thumbs
you flip, flip, flip until the edges are used up. Then you
grab another scraper or “pick up” the edge of the one
you are using if you can and if you know how to.
The common wisdom is to joint the edges with a file,
but I usually just use a diamond stone and hone the faces
too…. which you wouldn’t do with a file. If I want a
fine cut I go to a 1200 or even 6000 grit waterstone
and sometimes don’t raise a burr for a finish scrape.
I use razor blades too. I buy them by the 100 pack and
you can dub off the corners with a grinder and then
they don’t dig in. Get the single-edge ones. They dull
fast but they are excellent in a pinch for little patches
of interlocked grain, finish flaws and more.
P.S. yes I know Gorillas lack opposable thumbs.
