Jack Monroe is the worst, because she fraudulently begs from ordinary people rather than companies. What she has done at times crosses the line into breaking the law.
Despite being successful, in the public eye for nearly 8 years, and coming from a middle class family, she still pretends to be hard up and struggling, using weasel wording and lying by omission. This causes ordinary people to donate money to her or sign up to her useless Patreon. She shamelessly lives in an expensive house filled with expensive goods (including a Tracy Emin artwork) while pretending she can only afford £20 a week on food for two people.
She doesn't fulfill her Patreon or Kickstarter promises.
A couple of years ago her kickstarter made £68000 to publish a book (much more than she asked for), but she didn't get round to it for two years and mostly didn't send backers the books they were promised, then cried bullying when they tried to chase her up on it.