I think it just depends on whether you are itching for a re-visit, or want to try something new. You’re becoming a repeat offender, so I’m betting this won’t be your last rodeo.
Re the Allerano — Boñar is on the Olvidado, so if you‘ve got lots of time, you could start in Bilbao and connect with the Allerano there. But if not, getting to Boñar is probably easiest from León, since Boñar is in the province of León.
Re the Norte - Yes, there’s lots of asphalt, but the
coastal alternatives thread gives you some options. And my unscientific, very impressionistic thought is that there’s less asphalt on the ”second half” of the Norte.
I think May-June is the Norte sweet spot. Everything is open, there are few tourists, plenty of pilgrims but not crowds. There is a lot of accommodation, especially if you’re willing to to to private places. On several occasions, four of us got two-bedroom, two-bath apartments for ridiculously cheap. These places would cost much more in high summer.
The “inland” sections of the Norte, from Ribadeo on, are pretty, nothing strenuous, kind of bucolic.
Let us know what you choose!