I have both, 600w OSRAM Plantastar and a EYE Hortilux 600w (LU600s/htl/en)
I am leaning towards the Plantastar since from what I have seen it has more lumens, info is different from site to site but most rate them at 90,000 to 92,000; while the Hortilux info is consistant at 88,000 lumens...