Currently, my most watched would be Kanna Yanagi. (probably a bit obvious with how many of my posts include her)
I think why I watch her so much is because she's reliable. She's streams a lot, so there's always more to watch. She maintains a comfy and wholesome vibe, so I don't have to worry about "stuff" like world news or internet drama while I watch. The big collab events she joins or organizes are also a bonus.

Gotta remember not everyone is wired the same way or responds to stimuli the same way.
Some sounds work great for sleeping, while others not so much. It might sound paradoxical, but silence also has a noise to it. For me, the noise of silence is hit or miss for sleeping, white noise is too sharp and annoying, and nature sounds are often a bit too distracting. What I've found works best for me is rounded brown noise.

Pokemon Emerald: I used to play it a bunch to escape reality. Now my mind just associates it with safe spaces. It never fails to cheer me up when I hear the ost or see pokemon from that gen. Only bad part is that I can't play for longer than 20 mins without feeling so cozy I fall asleep.

Guilty Gear Strive: Strangely relaxing once I got a hang of the controls. I just play a few rounds against the AI for a pick-me-up. Not sure if it's still uplifting at higher levels.

Muse Dash: The music and cutesy artstyle are so overwhelmingly positive, it's hard to stay negative when you're in the zone and grooving.