That is a tough one, both were amazing but never the best, and both got underrated. With an exception of few seasons, their primes were mostly on different times despite being ss old as each other, mainly because Griezmann was a late bloomer, while Hazard career ended early.
I would take Hazard, just a hair above Griezmann.
Hazard the better player, Griezmann the more accomplished one, by far.
If you take International career out, Hazard actually has bigger trophy cabinet, though he was a no factor in his titles with Real Madrid.
But Ligue 1, 2 EPL, he was best player in EPL at some point. He also played for a Belgium team, whom while had amazing players, weren't anywhere close to the amount of talents French had.