Big events/tournaments are basically like TV coverage of sports, with similar production values. Examples:
YouTubers that also do streams, personality is important. I personally find this kind often to slow and with to many interruptions, so I don't really watch them. But they are popular and seem to be a great way to make money (compared with just YouTube).
https://www.youtube.com/watch?v=DjCGn1wo4kQ (mostly strategy/simulation-type games, relatively small following -> interacts with subscribers a lot, names ingame-things after them ("hi $name! weren't you a dwarf that lost both arms once?").
EDIT: he is also streaming Ludum Dare this weekend, for another type of streaming content: https://www.twitch.tv/quill18
https://www.youtube.com/watch?v=uegnAQD1hRs (Minecraft player, relatively random pick)
There is also the category of competitive players streaming just playing (and since competitive play takes their attention, there is not much interaction with the audience. But you get to see how somebody really good at a game plays like and hear them explain their logic). Don't have good examples available though, since I don't play competitive games.