Herman Miller Aeron (Remastered). It's a hefty price if you look at 'regular' chairs, but once you have had one for a while, you can't go back to anything else. The amount of time you spend in that chair is insane. So, naturally, that, and whatever it takes to get good sleep.

Also, a Logitech MX Master 2S, again because I use it all day, every day. They tend to become a bit stiffer over time it seems like, so I've had to replace them occasionally, but far, far better than Apple's approaches to mice or touchpads.