Well, I lack the online dedication to get into fighting games, but love watching others do it, so I watch Maximillian Dood a lot. He's a nice guy, and fun to listen to, and has a lot to say about various fighting game franchises. He's also great at them. My only warning is when he reviews other games. I'm sure he's giving an earnest opinion, but he's a little easy to please and seems to be satisfied as long as the game has you doing cool stuff, regardless of the mechanics behind them. Still, he has maybe 2 or 3 of those in his repertoire, so I mostly watch his fighting game videos.
When it comes to being informed on games, I follow Totalbiscuit a lot. Every once in a blue moon, he says something I don't completely agree with (I don't care as much about frame rates as him, for example), but even then I find most of his videos to be pretty well thought-out, and filled with the very thing he expects from everyone else: Open honesty about what your opinion should mean to others. For example, when judging a game, he'll let his viewers know if he has a reason to feel biased about the game. I also think his "First Impressions" videos can be very informative about games that just came out. I've heard the occasional argument about something he's said on Twitter, but I don't use Twitter. Perhaps another side of him shows on Twitter.
Recently, I started watching videos from Skallagrim, a man who is all about medieval weapons. He makes comparisons between flashy fantasy sword fighting and practical realistic sword fighting (for example, spinning is completely useless unless you're also dodging as you spin), he explains the various advantages of different weapons, he answers requests from viewers about how useful or useless weapons or maneuvers in certain video games would be in real life. Typically, I prefer flashy fantasy to pragmatic realism, but I still find his videos interesting.
There's a Let's Player named WolfieGGnS. He plays God Hand on hard difficulty and makes the game his playground. Anyone who has played God Hand will want to see this.
Then there's Zemalf. Not much to say here. He does Let's Plays and I find his Finnish accent to be soothing.
