Happy Isles

Mythical islands Also known as the Isles of the Blest (occasionally spelled blessed) in English and Fortunate Isles. The form blest occurs in Byron and Tennyson. What are they called in Greek?  There is a more or less standard name, although the precise form may vary:  Τα νησιά των μακάρων  or οι νήσοι των μακάρων.  Which form would you choose for this text, and why?