Eh, the more I think about it, given WB's current apparent lack of desire to do ANYTHING with Superman on the movie front, I find myself leaning toward taking advantage of that to build toward a soft reboot with a new cast...using a trilogy of stand-alones based on his supporting characters:
1st movie:
Steel, set after BvS when Superman is dead, with John Henry Irons as a member of the Army's reverse-engineering team assigned to the Scout Ship; an armor suit made of an Earth-based Liquid Geo analogue Irons has created; Metallo as a secondary villain, an Iraq War veteran crippled during Black Zero who's subjected to a much more unstable Liquid Geo analogue created after Irons quits the project; the Eradicator as the main villain, an A.I. encoded in Zod's Command Key programmed to complete his General's mission by any means, at any cost; and Sam Lane as the overarcing character of the trilogy, a sort of anti-Nick Fury who believes humankind shouldn't be looking to gods and monsters for help because we don't know when they'll turn on us.
2nd movie:
Supergirl, set during JL when Superman is dead and/or amnesiac, canonizing the MOS prequel comic with Kara Zor-El living as an amnesiac herself in a halfway-house in a northern Canada mountain town (after fishermen found her newly-thawed body adrift and afloat not long after Black Zero); her powers just now manifesting after being stunted by a hundred-thousand-year nap in the ice as the town is besieged by a stray group of Parademons; and the entire affair drawing the attention of not only Lane, but also an intelligence who's been keyed into our satellites and Internet since they first came online, one kept alive through the ages by bionic components, one who has kept endless watch from the stars for any sign of his long-lost daughter's Scout Ship...yep, Cyborg Superman by way of The New 52, a.k.a. Zor-El.
3rd movie:
Superboy (Conner), set about four years after JL but located mostly in space, with the first 15 or so minutes focusing on the top-secret efforts of CADMUS, reluctantly supervised by Lane, to create a programmable Superman clone via their own version of the Genesis Chamber; Mongul as the big bad, hiring Lobo to go to Earth to "collect" Superman as a new "recruit" for Warworld, and Lobo instead chasing the escaped teenage clone because Lobo doesn't pay enough attention to what goes on on Earth to know Superman's a grown adult; Mongul getting ticked off as a result and hunting both of them, with Conner bonding with one of Mongul's security dogs, a cloned Kryptonian wolf-hound *koff*Krypto*koff*; and, following on the endings of Steel and Supergirl, Kara showing up halfway through the picture in the Scout Ship as a surprise (especially for her) rescuer.
And THEN, and ONLY then...
4th movie:
Superman: Rebirth, based on what its title infers - the first two Superman arcs of DC's Rebirth event (with a dash of "Revenge" from later on tossed in) - a new Clark and a new Lois, a full 10 years on from JL married with a preteen boy of their own whose powers are kicking in. Three-act structure a la Superman: The Movie - the first act focuses on Clark's efforts to protect Metropolis AND his family from a second, CADMUS-made Doomsday with nary a Kryptonite spear in sight; the second act, Clark helping Jon cope with his powers after the boy's first use of them ends in disaster, while Lois investigates just what the hell would possess (
hint, hint) CADMUS to create another Doomsday (a task made more difficult by the fact that Doomsday II slew the entire team present to oversee his creation, not to mention her own dad's general lack of cooperation); and the third act, of course - showdown at the Scout Ship/Fortress (once again crashed in the Arctic following the events of Superboy) against the Eradicator, who's revealed to be working on behalf of Faora, whom he intends to release from the Phantom Zone to avenge Zod and complete his mission (and who it turns out was able to influence CADMUS' techs to create Doomsday II from within the Zone) with the aid of Zor-El and the "recruited" Mongul and Metallo, having sent the Justice League on a goose chase that will effectively prevent them from appearing in the movie...leading to the rallying of the entire Super-Family up to this point: Clark, Lois (in an improved Mech Batsuit - a wedding gift of sorts from Bruce), Jon, Irons, Kara, Conner and Krypto.
Yes, yes, I know this means there's two Superboys - to that I say, "Martha"!
More seriously, though, I would actually avoid having Superman appear prior to Rebirth, partially to get enough distance from what came before so as to better facilitate the re-casting of the character, and partially to make his ultimate return to screens an EVENT deserving of its own movie instead of a just a measly cameo in somebody else's (which is also why the first three stories are set in the timeline that they are). Also, switching the background antagonist to Sam Lane helps get away from Luthor and creates a more personal source of conflict for Clark and Lois, as does setting up a live-action version of the Rebirth-era Revenge Squad with the end purpose of re-introducing Faora - it'd be the REAL payoff of the Necksnap, a consequence that would come back to bite Clark in the ^$$ in a way that Doomsday, or frankly ANY other Superman villain, never could (in fact, I'm not so sure I wouldn't swap out Corben for Braverman as Metallo, since he was already in MOS and that'd be one less Kryptonite-powered villain to fall back on). From there, then, I'd focus on Superman without any larger regard to the DCEU in general.
