What are the benefits of using emacs auto-fill-mode?

I am wondering whether I should disable emacs auto-fill-mode it or keep it.

Why would I want to disable it?

Why would I want to keep it?

Are there any factors other than personal preference, or anything that may influence my personal preference?

I guess a good rule of thumb is whether anyone else will be looking at the file, and whether they have a reasonable expectation the text will be filled. If it's going to be filled text, you might as well use auto-fill.

I'm not sure there is a single answer, but I use auto-fill in some modes and not in others. On for things that are commonly understood to have a column limit: code [comments], commit logs. Off for free form text notes, org-mode, etc. There's no reason it has to be used globally.

I used to use auto-fill religiously but have since switched and turned it off for things like text files, using longlines-mode instead. As 0x4b says, though, it somewhat depends on your target audience and whether or not you believe they have an auto-wrap function in their non-Emacs text editor of choice.

For human readable text files, it's almost a standard for a line to be 80 characters long, and not more than that. If you want to obey this rule, auto-fill-mode will certainly help you. Yes, there are editors that will do automatic word wrapping for you, but if your intentions are to write 5 lines paragraphs in more than one line, then auto-fill-mode will certainly help you.

When writing anything that is not computer bound (configuration files, source code, etc...), I always turn on auto-fill-mode. It's there for a reason. Use it when appropriate.