I've been using Multi-Edit since version 5, many years ago. Its original strength (IMO) was its support for Dbase and Clipper programming, as well as a few others.
It has an extensive macro language, and the macro source comes with.
I own the current version, but a few months after upgrading, I discovered that it doesn't support unicode. So, if you try to edit items with, for example, Chinese characters, you get garbage. I wrote to them about this, and they said they had no plans to ever add support for Unicode. Since I now work on a lot of items in China, and other places, this means I only use it infrequently these days.
I don't recomment getting it, because many free editors will do much the same, although perhaps the free ones don't match the breadth of languages supported.