Ummm that not an easy question, lol.
Here my inaccurate (probably) list:
1) Twenty Øne Piløts (duh)
2) Isabelle Hyde
3) Mr. Chipotle/ CrankthatFrank/ More
I only really watch two YTers, so:
1. MacDoesIt
2. Lucas
I’ll give my third place to Jenna Marbles. I don’t watch many of her videos but she seems like a cool person.
Edit: I just remembered Starkid/Tin Can Brothers. They get second place. Lucas in third.