I manage a large forum and we use BBCode. I recently "open sourced" our rules (https://github.com/minecraftforum/rules) and during building the system you see there I made the decision to opt to use Markdown over BBCode -- what everyone that uses the forum is used to.
BBCode isn't inherently "bad" if you're just writing something and won't ever edit it again but for anything that you will need to edit / review in the future it can be a serious pain in the ass to look through.
These are the two examples I used:
### Title here
This is some text [with a url](http://google.com)
vs.
[size=6][font=arial, helvetica, sans-serif]Title here[/font][/size]
This is some text [url="http://google.com"]with a url[/url]
BBCode was written to be written, it's no more difficult to write
[url=http://google.com]google[/url]
than it is to write:
[google](http://google.com)
but when reading the source (for maintaining) it... sucks, because it feels un-natural. With the Markdown version of linking (to pick a basic example) you can read a sentence how the person reading the processed version would read it:
A search engine called [google](http://google.com)
That reads as "A search engine called google" and then you see that google is a hyperlink. With BBCode it would read:
A search engine called [url=http://google.com]google[/url]
So first you read "A search engine called" then you see it's a URL and then you see "google". It can get very frustrating when you're looking at huge swathes of text written in a similar style.
> The overriding design goal for Markdown’s formatting syntax is to make it as readable as possible. The idea is that a Markdown-formatted document should be publishable as-is, as plain text, without looking like it’s been marked up with tags or formatting instructions
Which is appealing to me, and many others I suspect.
