I'm not familiar with ChatGPT but I have Grammarly and find it to be a major pain in the ass. For one thing, it often gives me another way to say what I've said that isn't better, just different. For example, it lit up my page in bright orange to insist I change "going to" to "will." But what pisses me off most is how often it's simply dead wrong. How so? I wrote an article over a year ago titled "Grammarly Sucks" and laid out many examples of why I call it the worst app I've ever had. And I'm currently in the process of writing a follow-up, in which I again include many of the app's errors, some of which are hard to believe could actually come from a punctuation and grammar "expert" app. For example, it suggested I remove "such as" and replace it with "like." Okay, all you grammarians out there know that, although "like" and "such as" are often used interchangeably, they are not actually synonymous; although we habitually do it, it is technically bad English to say "like" in place of "such as." But this is just one of many things Grammarly has not been programmed to know. If you'd like to know more, be on the lookout for my "Grammarly Sucks" pieces, in which I lay out its screwups in excrutiating detail.