Ranked in these QuestionsQuestion Ranking
Pro Really fast
It is written in C. It is up to 10 times faster than ack.
Pro Simple syntax
Pro Ignores files in .gitignore by default
It ignores file patterns from your
.ignore. This can be a bit buggy though.
Pro Supports PCRE RegExp
Supports RegEx like look-ahead/behind (only fixed length lookbehind however).
Con Cannot add custom file types
All file types ag is able to search for are baked into the executable. There is no way to add new ones neither via command line nor via (the not existing) config file. The only way is a pull request on github and waiting for a new release.
Con No config file
You are not able to define options in a config file as there is none. (You have to use a shell alias or wrapper script to get your default options.)