As opposed to Chatfuel which was so easy to use, I found Manychat extremely complicated to create bots with. Maybe it was like this for me since I was used to Chatfuel, but I just couldn't figure out Manychat's 'Flows' options, despite reading their online material. I built several flows and published them but wasn't able to get my leads to trigger them.
The 'highlight' of it all was after I created a flow I wanted to later change and clicked the 'Revert to Published' button, thinking all my recent changes will be reverted. It completely deleted my entire work (not only the latest changes) and I couldn't reproduce it.
The worse thing was their customer service - I titled my ticket as urgent (I have huge marketing budgets bringing leads to this bot) but they responded over a week later. Then it became even more frustrating since they gave me numerous solutions which had NOTHING to do with my issue. They just couldn't understand what I'm talking about, suggesting that they themselves don't use their product.
Exhausted, I asked them to cancel my subscription. They did refund my money for that month, but a month later I found out they actually didn't cancel my subscription and kept on charging me! I went ahead and canceled my subscription myself, and there - surprise, surprise - found out that cancellation is only valid from the upcoming month. So you need to pay for another unused month.
This awful experience cost me time and money and only rewarded me back with frustration. Go with Chatfuel.