Jenny Nicholson is hands down my favorite YouTuber if for no other reason other than because her videos always expose me to some thing or subculture I knew nothing about while keeping it exceedingly entertaining. I love that she doesn't have a static release schedule and just puts out videos when they're done.
I would highly recommend her Last Bronycon video especially. Very interesting and detailed "dissection" of the good and bad parts of the fandom.