Beyond Compare is one of those programs that essentially does one job, but it does that one job so well that it is well worth its $60 price tag.
The software focuses on comparing files and folders and letting the user drill down into specific differences that can be merged, exported, reported on, etc.
I maintain several processes in which I need to drill down to specific differences between different versions of large text files. There are a lot of tools I could (and have) used to do this, but Beyond Compare makes it trivially easy to set up a particular filter for just the changes I need to monitor. Then I point Beyond Compare at the files, and in a few seconds, I have an exportable list of just the differences that I’m interested in for the next part of the process.