DXF files are more problematic in my experience, and may require that one learn a CAD tool (I’ve never used LibreCAD for anything beyond opening a file and re-saving it as a “MakerCAM SVG” and the one time I tried to do anything wasn’t able to find a matching point in the manual so dropped it).
SVG files are standard and widely used, and I’d argue that Inkscape is the de facto standard for editing them.
Either approach would work for the sort of work you note, but SVG files would be simpler I believe (there are more problems w/ DXFs on the tech support queue), and arguably, a 3rd party program would not be necessary since Carbide Create supports the sort of work you describe: