Which one places higher in the tiers for its respective game? Meh, probably MKX Sub, although he's low mid, still a lot better than MK9 Sub.
Which is a BETTER character however, in terms of playstyle and design? MK9 easily. He's a real character, all his abilities worked, and he wasn't what MKXSZ is, a character who relies on his above average normals and a workable 50/50 just to barely compete with his tiny ass damage output, and then a crappy Ice Clone tacked on top of it. MK9 Sub was built around using that Clone and it was a working tool. Predator's Trap is worse than SZ's MK9 Clone and it's still leagues better than MKX's, prompting a mass exodus to this character even from Tom Brady the most diehard SZ player ever.
Sorry, but I could justify playing SZ in MK9, it's not about being top tier, he played like Sub Zero. MKX version plays more like Blanka from Street Fighter at best