For developer work, it can automate an entire sequence of GUI annoyances into a hotkey. I'm making this sequence up because I don't recall how it exactly went, but the volume of bizareness was about right. AHK helped me painlessly build JAR files in Eclipse. I'd hit F12 and:
AHK would pull up file menu, export menu, select java, type jar filename, hit next, select jar file, confirm overwrite, next, next, select seal the jar, yes overwrite, click that one random dialog button that's bizarrely not hotkey selectable, type main class as 'default.java', next, confirm, click finish. Click confirm again despite finish because GUI. And bam, another JAR file ready to test.
Well, you always get to weigh the effort of rebuilding a toolchain vs working within the existing clunky toolchain. However, I daresay that reimplementing everything that eclipse does for java is no trivial matter and for a day-long project, not worth my effort.
Though not everything can be done with different development tools and AHK is a versatile swiss army knife. It can also do things like hotkey to make any window stay on top, send window resize message to a runaway or disobedient window, or be hotkey window clicks for games. I use it in stormworks to make my own shortcuts to edit / wiring / mirror buttons since they're 54 inches apart, and hopefully this all shows where AHK's versatility shines.
AHK would pull up file menu, export menu, select java, type jar filename, hit next, select jar file, confirm overwrite, next, next, select seal the jar, yes overwrite, click that one random dialog button that's bizarrely not hotkey selectable, type main class as 'default.java', next, confirm, click finish. Click confirm again despite finish because GUI. And bam, another JAR file ready to test.