I would ultimately go with Thanos because Zoom can only beat him by physically beating him down, and I don't recall anyone ever knocking Thanos out through physical force, in fact I can only recall one time (ignoring Squirell Girl) that Thanos has been knocked out and that was by the Maker/Beyonder with a huge energy blast.
Thanos can create fields to protect himself regardless of what a certain somebody on here says, his tech shields are always with him like Iron Man's are to him so he could use those too, he doesn't need to prep to use them. Then he has energy manipulation, matter manipulation, mental powers, and a top tier strength and durability wise, he would win eventually.