Btw. It really depends on what kind of person you are. I've been part of the youtube scene since 2010, so I know my way around pretty well. I pretty much browsed all the anime/ manga reviews, all the kinda well know gamers to popular gamers, comedy shows, and pretty much everything. I used to watch yt like it was my life. I still do, but to a lesser extent. With this said, my personality changed over the years.
When I was 14, I watched Pewdiepie (when he only had 100,000 subs) and CaptainSparklez and Seananners
When I was 15, I watched Those people + A TON of COD players (Muzza Fuzza, Codplay247, ect), Antvenom, RWJ, ect, ect. (basically all the popular YTubers)
When I was 16, I began to watch less of those people^ an more of people like penguin0, Vlogbrothers, Vsauce, and other science channels, and allshamnowow and XCal
When I was 17-18, I completely quit watching cod ( i stopped playing years ago) and now, here is my favorite Ytuber list (HIGHLY RECOMMEND):
Seananners (short, sweet, funny, daily)
XCalizorz (old school youtuber gamer, badass, streams daily, posts gameplay with unique commentary style. He's a "you treat me nice, I treat you nicely, or else I'll kick you" kind of guy. He's stern, but his fanbase is loyal af)
Penguin0 (funny, sardonic, sarcastic, monotone -in a good way-, a good guy -donates ALL of his yt money to charity-, super random gameplay videos)
Inside Gaming by Machinima (only good machinima program left. especially their saturday GTA special. omg. i always end up crying after watching those)
Vsauce/minutephysics/Veritasium (for your scientific needs)
ZeFrank0 (sounds like morgan freeman. what other reason do you need)
and some other small comedy and animation stuff
oh and anime/manga reviews:
Swayer7mage (for a critical and cynical review)
Double4Anime (for a fanboy and hyped review)
hope you guys can take a good look at this list.