Now, of course, I'm going to say that - Adaptavist acquired SR about 15 months after I joined, so I have no problem with anyone accusing me of bias and self-promotion here.
But I was using SR for a long time before I joined Adaptavist. When I started with Jira (which was the only Atlassian application available at the time!), I ended up in the consulted process of having to create plugins (now "apps") to do clever things with it, or spending ages trying to make some other plugin (often plugins), do it. I was trying to move a bit away from being a developer but got pushed back when we needed Jira to be clever.
Scriptrunner enabled us to write just the snippet of code we needed without a plugin. 6 lines of code instead of 6,000. 60 seconds to implement it, not 60 minutes.
The others I pretty much insisted on installing everywhere I went were
The content formatting macros - especially after they built in the LaTeX macro, so I didn't have to do that installation as well
The Jira Toolkit - there's always at least one thing in there that your people will want to use. If I were to move to Atlassian, I'd want to be the Product Owner for that and get it installed on all the things, because it is so useful. Nothing huge, nothing life-changing, but one of those things that makes it all a bit easier without you really noticing it. Message fields, participants, exposing properties, and and and. It reminds me of pTerry Pratchett's "Small Gods", where he describes the smaller and under-rated gods that we all know, but rarely pay attention to. For example, Anoia, Goddess of Things That Get Stuck in Drawers.
