If Aquaman were to FINALLY get a movie, I think he ought to get his own trilogy.
Recently, I've been thinking about the story arc, 'The Others' and how cinematic it felt. Of course, making this Aquaman's first film wouldn't really capture the epic feel of the story arc, and should be reserved for a third film.
Of course, this would mean that Black Manta would have to be the villain for the first solo film (no complaints here, how incredible sleek would Manta's armour look on screen?).
That leaves the question of who should be the villain for the second film? Ocean Master IMO.