Let's plays are by far the easiest. You already need a decent computer for any kind of video editing and content creation, so all you need is a mic and to not be the dullest person on earth. Most let's players don't even edit their footage. I used to make gaming videos and it was definitely a LOT easier than what I do now, and much easier to find an audience, too.
The hardest would be people who make short films and stuff. I can't imagine writing scripts, planning shoots, getting actors together, etc.. It's crazy. Even harder than that is people who do effects-heavy stuff like FreddieW's old stuff. Not only did he have to organize actors and shoots, but then had to spend all that time making SFX on top of it? I definitely wouldn't want to do any of that. (I say his old stuff because he has a whole team doing all the post-production work now so I'm sure it's way easier on him on a day-to-day basis than it was when it was just him and Brandon doing everything)
An underappreciated one is animation, though. You don't need to buy a camera or even really have a fancy computer to do it, but having done my fair share of animation in the past, it's SO TIME CONSUMING. It drives me insane when I see comments on animators channels that are like "make more videos!". People have no idea how long it takes to write, storyboard, keyframe and then draw every. single. frame. It's insane work for insane people and it takes forever. I don't know how some of them even consistently release decent quality content. Props to animators.
My content falls squarely in 'medium-hard' difficulty. I spend half a day shooting a video (3-6 hours usually) and then 3 times that editing (easily 15-20 hours) just to release one video, and I'm not even counting the time photoshopping thumbnails and adding tags and stuff, but every Youtuber has to do that anyway lol
