quill18 - Strategy games
SBFMadDijinn - Strategy games, some FE/LH video Let's Play videos
Das24680 - Strategy games, also very good FE/LH videos for people that are new
Beaglerush - XCOM
Day9TV - SC2, I would recommend him even if you don't play Starcraft. He has a number of good videos on improving gameplay in general and game-life balance.
totalhalibut - Total Biscuit, VERY honest reviews. Can be a bit of a shock jock.
NanosuitNinja - Anno 2070, Brits are awesome. If you ever want to try Anno 2070 you should check his videos out.
Otherwise, check out Geek and Sundry