I think
Blythe has a lovely sound and meaning, but I definitely see it more as a middle name. I agree that is sounds lovely with just about every first name!
Sophia Blythe and
Eleanor Blythe are my favourite of your combos (I actually know an
Eleanor Blythe, if you can believe it).
Isabella Blythe is my least favourite only because the B sounds are a bit close for my own personal comfort.