Teksyndicate, LinusTechTips, Drunkenpeasants, Vsauce(1,2,3), e33rock.
There's probably some others out there that I watch quite often but I think these tend to be a bit more often. JonTronShow mentioned earlier is quite entertaining to watch, and one way or another I tend to get a dosage of some popular let's play channels too.
Half of my time online properly consists of YouTube one way or another, scary in it's own way.