Wow, surprised I didn't find this thread sooner. A lot I could mention, but I'll just start off with this:
Pretty much any video by JIMBOTHY
I cannot stand this guy. In his videos, he talks in this phony voice almost the entire time and likes to shout into the mic at random times. Now I get his videos are intended to be jokes and such, but that doesn't mean they can't be terrible. Now I have a sense of humor and I know how to take a joke, but this guy just tries way too hard to be funny in his videos and I don't find him funny at all. I can't really pick one particular video from him that is the worst. I find him to be the most annoying Youtuber ever and how he gets 750,000+ subscribers is beyond me