I don't know if I can say I have a favorite since there is so much variety, so I'll just list off some of the ones that I love.
Proton Jon
One of the first few Let's Players, his videos and streams on
Twitch.tv are incredibly entertaining and insightful.
davidangel64 aka X
Known best for being one of the first to make a full fledged Let's Play of Minecraft, nowadays he's known for his calm approach to the first person shooter genre.
SeaNanners
Although the style of his gaming videos has change drastically through the years, they've never quite gotten less entertaining.
EthosLab
Often described as a "Technical Minecraft Player", he's known for helping making things such as redstone and mob traps popular in the community in its early days.
jacksepticeye
Somewhat of a newer Youtuber, he gained a humongous following last year because of his incredibly ridiculous yet at the same time down to earth personality.
Every Frame a Painting
A collection of video essays about movies, even those who aren't that aware about how filmmaking works can understand these very well explained analyses of scenes from movies.
Tom Scott
If you want to learn some really interesting facts about random things, this would be a great place to start.