The only streamer that I really watch is Brian Kibler, who plays Hearthstone and used to be a pro MTG player. I think the reason I watch him and no one else really is because he's older, doesn't rage, includes his wife in his stream occasionally, and provides insights into his decision making process. He's just good natured and it's the closest thing I've found to those poker tournaments that I used to watch on cable at midnight.
Likewise, I watch almost exclusively Firebat (with a bit of Kibler every once and awhile).
He does a really good job of balancing being funny and interesting (as a person), and giving really good insights into his thought process in playing Hearthstone, building decks, and competing.
Different personality types appeal to different people (naturally). I'm a fan of Scott Manley, who never rages of screams, but mostly provides educational and entertaining commentary on what he's doing when he's playing a game.
But I also like Funhaus, which is effectively a podcast where a group of people plays a game in the background. (They also have an actual podcast which is literally that.)
Check out Jason Somerville (JCarverPoker) for some great poker streaming, when he's on. He goes in spurts and it feels about time for a nice one. He has a great personality and is much less negative than a lot of the other poker streamers.
