I don't see Hulk's durability as the problem.
It's his nearly instant regeneration that is the problem.
Having said that AQ could take all 3 scenarios but I can't see Hulk taking out 2nd scenario Aquaman.
Now in the first scenario Hulk has the more chances. It could go either way but if AQ plays his summoning power clever and swarms Hulk with Krakens, Devilfishes and the like while he keeps stabbing and cutting a to slow to react Hulk I think he could pull a KO.
Second scenario is all Aquaman IMO. The Water Hand has some crazy feats and all of the above tactics can also be applied.
Third scenario is like the first one although the armor gives a further edge to AQ.
Plus people forget that if Hulk can breathe underwater, he is pretty much done for due to one of AQ's more vicious battle tactics...
In the 6th AQ series (before the Sword of Atlantis stuff) a supervillain named the Eel actually had AQ one the ropes until he did a very simple thing. He ordered all of the microscopic organisms inside the Eel to f@ck him up. And thus the villain was done for, going down in extreme pain and agony.
So with all of the above being said I give AQ a small edge on the 1st battle, a big edge on the 2nd battle, and a moderate edge on the 3rd.
Just my opinions.