Some advantages of CodeWeaver are that it is compiled, so it might be faster; you can grab a compatible executable from the releases section instead of using `go install` so, no dependencies. You can manually specify what to exclude via a comma-separated list of regular expressions so it might be more flexible. I never used Repomix so, those assumptions might not hold. On the other hand, remix seems to be awfully more complete, a full-fledged solution to convert source code to monolithic representations. I wrote CodeWeaver because I only needed something that worked and, occasionally, I could trust to keep sensitive data away from sketchy LLMs (And wasn't aware of other solutions).
I simply have a bash script called printall which takes in some args, and outputs markdown codeblocks with filenames and a tree. One of hundreds of scripts built up over the years.