Hi David,
I think it depends what you expect from your next camino. The Primitivo is rather tough with beautiful landscapes. There are not many possibilities to vary your stages before you reach Lugo. So most likely you will form a camino family.
The Inglés which has not called me so far, seems to be rather flat with unspectacular landscapes.
The camino to Fisterra and Muxía is nice, especially if you are heading for Fisterra first. It attracts people from various caminos but also people who do only walk this part. So you may have many interesting conversations about various caminos and get new ideas for future pilgrimages. But you can not expect that the travel companions with whom you have reached Santiago will continue to Fisterra and or Muxía as well.
Also it is rather unlikely that you will experience something like a camino family on such short caminos as the Inglés or the Fisterra-Muxía, because there is plenty of accomodation and you can do very variable stages (e. g. 3-5 stages to Fisterra, another 1-2 stages to Muxía, 4-7 stages on the Inglés).
BC
Alxandra