what do you think about this one? It uses Palm stalk fibers bristles?
https://www.amazon.com/Cuisinart-CCB-399-Pizza-Stone-Cleaning/dp/B00N0L5QLO
Get a non-metal bristle brush. I have this one, and the bristles burn away after a while, but it has lasted me years as long as you're not super careless with it. Plus, zero chance of metal in your food. (I never ever ever ever use metal grill brushes anywhere, too easy to miss a broken bristle and ingest it.)
Interesting, hadn't seen the spinners before. How are they working out for you?
I was planning on buying this 18" brush, think that's long enough or should I be looking for longer?
I picked up one of these from Amazon : https://smile.amazon.com/dp/B00N0L5QLO
It has "palm bristles", so you don't have to worry about metal shards. I just got it a few weeks ago, so I can't speak to how well it holds up but so far it's pretty good. The scraper edge helps get the crusty stuff off as well as push the last bits of stuff off the edge of the stone.