I've worked on most of these sites, so if anyone's thinking about joining this is my opinion.
Cloudworkers - worked here for over a year, found it hell. I did like the entertaining 'motivational' emails but there were a lot of irritating ones too, threatening to sack people etc. I preferred the monthly pay rather than weekly. Didn't enjoy the shift booking, but I would miss a lot of shifts and nothing was ever said. You will have emails day and night asking you to log on, and they're always really dramatic too "CRITICAL LEVEL OF MESSAGES - LOG ON RIGHT NOW!!!!" at 3am. There's a high percentage of other admins who clearly can't speak English properly, the quality of the other workers was dreadful. One message in perfect English and the next in the same conversation in broken English with no punctuation etc. It also really slowed me down when they forced me to work an additional platform at the same time. I quit last year because it made me so depressed I couldn't hack it anymore. I do miss the monthly pay though, the traffic is huge and once I made £800 in a month but I was a mess at the end of it.
Chatfromhome/ Admin Hub - I've been using this for about six months now, I like that it's 15p a message, adds up a lot more quickly. There are always plenty of messages to reply to most of the time and having the option of using a phone too means I can answer messages whilst I'm out walking, waiting to go into an appointment, standing in the checkout at the supermarket etc... you can voice type on your phone too. You don't really have to make any notes either which makes it a lot quicker. The only thing that annoys me about it is the guys all seem to send the same message every time... "Wow I'm so horny for you baby, did you have a play today?" literally the SAME damn message from every one of them. So it gets tiresome pretty quickly trying to paraphrase replies. You can take three weeks out if you want and only have to do 75 messages during the week after that to keep your account active.
Operator Chat - I signed up to this recently but I don't like it personally and I think I'm going to quit soon. The layout is a lot better than other sites, but they pull your messages up for the stupidest stuff (like using an exclamation mark) and almost all of the messages you have to type are over 250 characters long. Even when you get a short one to reply to, they will pull up your message and say you need to type more to make it more 'well rounded'. It takes forever just to get up to the first bonus and even if you did over 1700 to get to the top bonus, it works out at 15p a message which is what you start with on Chatfromhome. There's a lot to remember too with the different colours the user is under, and you get in trouble if you don't.
Contentmods - This was a decent one, I did quit it about a year ago. You only got paid for replies but I think it was 15p a message. They'd always have the same men messaging, so you'd get to know them pretty well and there was a group chat where we'd all laugh about what the men were saying. They'd also give you other tasks like making profiles where you could make up your own characters which was a lot of fun. The management were really friendly too.