I just wanted to note that `rx' is in many cases much easier to write and
understand than even PCRE. I'd recommend learning and using `rx' if you are
annoyed about backslashes or readability.
While I'm sure that is true for lot of people (and for those, the newly announced xr package helps here), others prefer to use the more compact regex syntax.
However, I don't think anyone would argue that the Emacs regex syntax has any advantages compared to pcre. I certainly need to wade through the Emacs regex manual every time I want to do slightly more advanced regex matching, followed by lots of testing.
When using regexes in regular editing (as opposed to elisp programming) it's even worse.
I'm most definitely in favour of pcre.
Regards,
Elias