grep came, then ack-grep, then silver-searcher and a few others, finally ripgrep. For most purposes, ripgrep (the one written in Rust) is the best of all of these tools, typically being the fastest and also the most Unicode-compliant, with the main downside being its non-deterministic ordering of output (because it searches files in parallel).

The only reason for using ack these days is if you’re already invested in a Perl workflow and can use some of the Perl magic powers, and don’t care about comparatively poor performance. That’s not many people.