Wouldn't 335 vs M3 be a more apt comparo? The X6 is in the M's price range.
At any rate, 335. I despise the X6. I don't know why BMW chose to copy the Pontiac Aztec...
'08 Black Saphire/Black Z4 M Coupe
RIP Gretta: Blue Water/Lemon 135i. Died to save me.