Hum, there's a bunch, tho I kinda don't follow them all at the same time, usually watch a few at a time before getting bored and watching some others for a while, and so on.
The Hearthstone usuals are Trump, Kripp, Savjz and Toast, I find the insights, the salt and the magic moments are much more enjoyable than playing the game itself, which is usually infuriating. Then there's some misc ones like Quill18, Marbozir and Aavak for the grand strategy and random indie games, they're good for finding new stuff to play or getting an impression of some games I might be interested in. TB is there for WTF's and his Shoutcraft stuff (tho I guess that isn't him playing it per se), usually an entertaining watch and sometimes I learn I might like a game I didn't think much of previously. Scott Manley is a chill dude for space games, always fun to watch and listen to him, regardless of the game played. Extra Play has a number of folks playing various games, usually with some decent analysis on top of it when they bring in specific game folks (plus the buggers got me into DS, never gonna forgive them that), more educational plays when I'm feeling like it. Jim Sterling for the utter and complete shit he's willing to dredge out of Steam Greenlight (plus he's a funny bloke), for the feeling of fascinated horror that some people are actually asking money for some of the stuff on offer. The Fragnostic is good for random old or horror games, but even if you don't like those that much, his rambling brit commentary is pure gold to just listen to, even without the games. Used to watch Yahtzee, but he doesn't really upload much stuff since he left Australia. There's also Life of Boris I guess but he isn't too regular with his game stuff, tho I guess that doesn't matter since he's pretty good regardless of the type of content he does.
Wow, looking at it now, that's a pretty big list there, but as I said, a fraction of it is watched regularly at any given time, usually depending on the mood.