Aside from the usual travel, politics, pointy things, history, and 'other stuff' fare, I've been enjoying Aquaholic's channel. Because I love torturing myself by looking at expensive power yachts I will never be able to afford in several lifetimes.
I also like Military Aviation History and Chieftan's Hatch. Great interior overviews of all the cool flying and rolling stuff from WW2.
For 'turn your brain off' stuff, well... everything listed here between this list and the others here pretty much IS all my brain/off stuff...
I've also been enjoying watching the Critical Role D&D campaigns. The cast is hilarious, and it's great for brain/off use or for playing in the background and sort of half-watching when exercising or cleaning guns or some other boring task that only requires 50% of your attention.
I also use some other
video streaming sites