There are several great Emacs search tools available! I have learnt lots when playing with these and reading their source code. You might even find you end up using these as well as deadgrep, depending on your workflow.
Counsel provides the command
counsel-rg (and similar commands counsel-ag and counsel-ack).
This uses counsel's incremental searching UI.
Great for: As-you-type search results.
ag.el allows you to use ag for
Emacs searches. I wrote it, but I've learnt a lot about good search
UIs since I built ag.el.
ag is not quite as fast as rg, so results come more slowly.
ag.el has a lot of search commands to memorise:
agag-projectag-project-filesag-filesag-regexpag-project-regexp
This only covers some of the possible filter combinations, and caused confusion for users who expected regexp search to be the default.
Results buffers here are much busier, showing superfluous
information. This is because ag.el is built on top of
compilation-mode, which isn't a great fit for searching.
ag.el has a few tests, but coverage is significantly lower than deadgrep.
Great for: Searching with ag, binding a different search to
different keys, and editing files from the results buffer using
wgrep.
rg.el targets rg, and the results
buffer shows what type of search occurred.
It's built on compilation-mode, and you can use rg-group-result to
combine results.
Great for: if you want a ripgrep tool with excellent test
coverage, you have compilation-mode shortcuts, or if you do lots of
searches for words (rg-dwim is excellent).
ripgrep.el, and projectile-ripgrep (part of the same project), is an alternative to rg.el.
This is also using compilation-mode without grouping
results.
Great for: ripgrep searches starting in the project root.
Socyl is a generic text search
tool that supports rg plus others.
Socyl is also based on compilation-mode, and does not group results
by file AFAICS. As it's generic, users must specify a search backend,
as well as specifying the directory.
Great for: Using the same search UI with multiple different search tools.
helm-rg targets Helm users.
helm-rg is a Helm frontend for
rg. In addition to the usual search features, it treats spaces in
search terms specially so you don't need to worry about order. This
neat feature means that foo bar is equivalent to
foo.*bar|bar.*foo.
Great for: Using rg with Helm, especially with multiple search terms.
M-x grep is a built-in Emacs command.
Users must specify the glob and the search term as part of a raw
grep command. This means your .gitignore is ignored, unlike rg,
ag or ack. This command also uses compilation-mode.
Great for: Doing a text search using only built-in tools.