Sorted by subscribers:

22.2M - Mark Rober: https://www.youtube.com/c/MarkRober
18M - Vsauce: https://www.youtube.com/c/vsauce1
13.5M - CrashCourse: https://www.youtube.com/c/crashcourse
12.3M - Veritasium: https://www.youtube.com/c/veritasium
10.5M - SmarterEveryDay: https://www.youtube.com/c/smartereveryday
7.16M - SciShow: https://www.youtube.com/c/SciShow
5.5M - CGP Grey: https://www.youtube.com/greymatter
5.48M - minutephysics: https://www.youtube.com/c/minutephysics
5.41M - Charisma on Command: https://www.youtube.com/c/Charismaoncommand
5.12M - Tom Scott: https://www.youtube.com/c/TomScottGo
5M - JCS - Criminal Psychology: https://www.youtube.com/c/JCSCriminalPsychology
4.63M - 3Blue1Brown: https://www.youtube.com/c/3blue1brown
4.13M - Numberphile: https://www.youtube.com/c/numberphile
4.06M - LockPickingLawyer: https://www.youtube.com/c/lockpickinglawyer
3.91M - Stuff Made Here: https://www.youtube.com/c/StuffMadeHere
3.75M - Casually Explained: https://www.youtube.com/c/CasuallyExplained
3.51M - Wendover Productions: https://www.youtube.com/c/Wendoverproductions
3.45M - vlogbrothers: https://www.youtube.com/c/vlogbrothers
2.82M - Johnny Harris: https://www.youtube.com/c/johnnyharris
2.82M - Code Bullet: https://www.youtube.com/c/CodeBullet/videos
2.75M - Practical Engineering: https://www.youtube.com/c/PracticalEngineeringChannel
2.7M - MinuteEarth: https://www.youtube.com/c/minuteearth
2.32M - Captain Disillusion: https://www.youtube.com/c/CaptainDisillusion
2.29M - PBS Eons: https://www.youtube.com/c/eons
2.21M - Half as Interesting: https://www.youtube.com/c/halfasinteresting
2.16M - Computerphile: https://www.youtube.com/user/Computerphile
1.97M - Adam Ragusea: https://www.youtube.com/user/aragusea
1.92M - Economics Explained: https://www.youtube.com/c/EconomicsExplained
1.55M - How To Drink: https://www.youtube.com/c/howtodrink
1.51M - Company Man: https://www.youtube.com/channel/UCQMyhrt92_8XM0KgZH6VnRg
1.44M - SciShow Space: https://www.youtube.com/c/scishowspace
1.37M - Defunctland: https://www.youtube.com/c/Defunctland
1.24M - engineerguy: https://www.youtube.com/c/engineerguyvideo
1.19M - CaspianReport: https://www.youtube.com/c/CaspianReport
1.15M - GeoWizard: https://www.youtube.com/c/GeoWizard
1.05M - Atlas Pro: https://www.youtube.com/c/AtlasPro1
1.03M - Domain of Science: https://www.youtube.com/c/DomainofScience
856K - Sixty Symbols: https://www.youtube.com/user/sixtysymbols
765K - SciShow Psych: https://www.youtube.com/c/SciShowPsych
537K - City Beautiful: https://www.youtube.com/c/CityBeautiful
484K - Todd in the Shadows: https://www.youtube.com/c/ToddintheShadows
416K - Whatifalthist: https://www.youtube.com/user/WhatifAltHist
360K - Welch Labs: https://www.youtube.com/c/WelchLabsVideo
331K - Brett Kollmann: https://www.youtube.com/c/BrettKollmann
212K - FINAiUS: https://www.youtube.com/c/Finaius
197K - Objectivity: https://www.youtube.com/c/ObjectivityVideos
167K - Geography King: https://www.youtube.com/c/GeographyKing
129K - That Is Interesting: https://www.youtube.com/c/ThatIsInterestingTII
115K - DeviantOllam: https://www.youtube.com/user/DeviantOllam
108K - Modern MBA: https://www.youtube.com/c/ModernMBA
67.5K - Bright Trip: https://www.youtube.com/c/BrightTripChannel
63.9K - MinuteFood: https://www.youtube.com/c/MINUTEFOOD
40.9K - National Park Diaries: https://www.youtube.com/c/NationalParkDiaries