I haven't read Lorca, so I have no expertise. I did, however, recently pick up the New Directions selected Lorca. For that volume, the editors selected, for each individual poem, what they thought was the best existing translation of that poem. So that volume may be a good bet (unless you want a consistent translator). It's a bilingual edition, too.
http://www.ndbooks.com/book/selected...-garcia-lorca/