I’m a logo designer who uses the title combo instead of Illustrator.
Inkscape - the cornerstone of my workflow - is very powerful and feature-rich, but unfortunately has no color management whatsoever, can’t embed a CMYK color profile or simultaneously exportf multiple files to multiple firmats, which makes the export process very tedious.
Affinity Designer, on the other hand, has the very features Inkscape lacks, but falls short everywhere else.
Thats’t why I use them in concert. First, I sculpt my design in Inkscape - in black & white - and then I transfer it to Designer for CMYK colorization - in a color-managed environment - and final export.
The two apps compliment each other very nicely. The only possible drawback is that you can only copy objects directly from Inkscape to Designer and not the outher way around, as Inkscape turns Designer vector objects into bitmaps.
Otherwise it’s a great option, provoded you aren’t required to deliver .AI files.
It costs no more than one or two months of an Illustrator subscription (for a lifetime Designer license).
Credit: Nick Saporito (Logos by Nick).