I did the Ingles, and so am biased - do the Ingles. For the following reasons:
1. It is far quieter than the Frances, even in the summer, so that you do not feel you walk in a procession.
2. Being much quieter, you feel you are on a pilgrimage
3. Accommodation should be available, but booking in advance helps
4. You walk the whole camino - gives you a larger sense of achievement than just walking the last stage of one of the larger caminos
5. Lovely coastal walks for the first three days.
6. Possible to walk the whole way and stay in hotels / B&B's or in alberges with private ensuite rooms
Suggestions.
10 June - arrive Santiago - transfer to Ferrol
11 June Day 1 - Walk from Ferrol to Xubia / Neda
12 June Day 2 - Xubia / Neda to Pontedeume
13 June Day 3 - Pontedeume to Betanzos
14 June Day 4 - Betanzos to Meson de Vento / a Rua
15 June Day 5 - Meson de Vento to Sigueiro
16 June Day 6 - Sigueiro to Santiago
17 June Rest day in Santiago
18 June - 21 June - 3 or 4 days walking the Finisterra - to Xubia then to Fnisterre
22 June - home
I found my accommodations on the Ingles from the Cicerone guide website and then booked directly
www.northerncaminos.com/accommodations
If you had a spare day, I would go to La Coruna for a night, on the way to Ferrol. Well worth spending a day looking around.