Comment by burntsushi

Fewer bugs?

And perf depends on your haystack size. If you have lots of data to search, it's not hard to witness a 10x difference: https://news.ycombinator.com/item?id=45629904

As for features that ripgrep has that ag doesn't:

* Much better Unicode support. (ag's is virtually non-existent.)

* Pluggable preprocessors with --pre.

* Jujutsu support.

* ripgrep can automatically search UTF-16 data.

* ripgrep has PCRE2 support. ag only has PCRE1 (which was EOL'd years ago).

* ripgrep has a `-r/--replace` flag that lets you manipulate the output. I use it a lot instead of `sed` or `awk` (for basic cases) these days.

* ripgrep is maintained.

* ripgrep has multiline search that seemingly works much better.

* ripgrep can search files bigger than 2GB. ag seemingly can't.

* ag has lots of whacky bugs.

e.g.,

    $ ag -c '\w{8,} Sherlock Holmes' sixteenth.txt
    9
    $ rg -c '\w{8,} Sherlock Holmes' sixteenth.txt
    9
    $ cat sixteenth.txt | rg -c '\w{8,} Sherlock Holmes'
    9
    $ cat sixteenth.txt | ag -c '\w{8,} Sherlock Holmes'
    1
    1
    1
    1
    1
    1
    1
    1
    1

Or:

    $ printf 'foo\nbar\n' | ag 'foo\s+bar'
    $ printf 'foo\nbar\n' | rg -U 'foo\s+bar'
    foo
    bar

Or:

    $ ag '\w+ Sherlock Holmes' full.txt
    ERR: Skipping full.txt: pcre_exec() can't handle files larger than 2147483647 bytes.

There's probably more. But that's what comes to mind.