I've had a bit of luck finding youtubers/twitch streamers who are content to let some dead air go by if they don't have anything important to say, and definitely don't do any yelling or screaming. It's a real nice change.
Partially I'm just making this post to share the few I've been watching the most:
Jagged Appliance, a Supreme Commander player and caster.
Growling Sidewinder, a DCS pilot who goes into detail about dogfighting and BVR fighter jet tactics.
Tasteless, a Starcraft caster who plays Brood War and chess in the Korean timezone.
brutalmoose is super chill and while his main channel doesn't really focus on games anymore (although his videos are always great), he streams on Twitch and posts the vods on his moose2 channel