I follow ZeroEmpires, Resonance22, Memb, and T90 most frequently, although my free time now wasn't what it once was. Resonance22 is excellent at making his videos accessible to newer and less experienced players while still providing solid insight, while Zak, Memb, and T90 generally tend to appeal to a more experienced crowd, I'd say. Memb's videos are absolutely hilarious, and I find myself consistently in stitches listening to his various catch phrases and animated commentary.
Spirit of the Law's videos and commentary aren't really applicable to competitive gameplay and are often inaccurate, but he brings a different approach to game analysis that I find rather intriguing, even if it should be taken with more than a few grains of salt.
There's also this Lord Basse guy whose videos on custom scenario design were pretty cool