I'd say Thanos will take this with mid to high diffculty.
There's some canceling out here between the two.
AP/Dura: Really, I don't see either holding a distinct advantage. Superman has the AP/Dura advantage over the likes of Thor and Silver Surfer though not by that much, IIRC. At the same time, Thanos is also superior to both the aforementioned characters. As such, the two will be duking it out for quite some time.
Hax: Superman doesn't really have hax to speak of. Thanos actually has a fair bit of hax but Superman resists almost all of it. The one ability Thanos has that Superman has no counter or resistance for is the Life Manipulation, which Thanos could use to just rob Superman of his lifeforce and basically kill him right then and there. However, Thanos doesn't know that he needs to do that and it isn't something that he does right away. So, Thanos does have a way to just up and win but it will probably take some time before he ever even tries that.
Experience: Thanos has been around causing problems in the universe for thousands of years. This includes wiping and subjugating entire populaitons by himself. He's also fought against numerous heroes and villians over the years. However, Superman has done much the same (except the whole genocide and enslaving thing.) So, really, I don't see anything that puts them above the other.
Stamina: Superman's stamina is basically unlimited under a yellow sun and Thanos' is so high that the thought of either one of them tiring the either out is...laughable.
Intelligence: In raw intelligence, Thanos beats Superman but that's doesn't mean all that much. Superman is used to dealing with geniuses like Luthor and Darksied, and Thanos doesn't have prep or anything to try and set something up. Not too mention that Superman isn't an idiot and is rather intelligent himself so...
Practical Options: Here is where I think Thanos has a definite edge on Superman. At the end of the day, all Superman can really do is punch, burn or freeze Thanos when it comes to offensive moves. Defense-wise, Superman resists most of Thanos' hax but has no special defenses. All he can do is evade or physically block attacks like most other beings.
On the other hand, Thanos can blast Superman various energy attacks (which he can emit from his hands, his eyes, or in an omni-directional release of power.), trap Superman in a block of pure force, and use his energy attacks to deflect other energy attacks. Thanos also has access to various forcefields to throw up to defend himself and teleportation technology to move himself around, giving him greater mobility.
Overall, I think that Thanos can win this but Superman will work him over and it won't be easy.