Because "best" is obvious a subjective statement, and you wanted to argue that...
Inkscape can make a CMYK-file, with an addon. It's pretty easy. Besides CMYK is only relevant is you want to print, and most graphics work today is for screens. It literally takes about 7 seconds to make it CMYK.
What feature do you need, that Inkscape can't do? Is it really the 7 seconds to make it CMYK, that breaks you?