Since The Force Awakens was so derivative, what kind of Episode 7 would I have written for Star Wars, if they put me in charge of the script?

I would have made it a gut-wrenching deconstruction of the original narrative where the New Republic is now in change, Luke and Han and Leia hold important positions of power, and they have to crush an uprising of plucky pro-imperial supporters. Han would be a ruthless fleet admiral, Leia would be a scheming politician on her way to becoming Supreme Chancellor, and Luke's New Jedi Order would be the secret police hunting down dissidents.
The opening text-scroll would be written as gushing propaganda for the New Republic, describing Han and Leia in particular in North Korean-esque terms.

I would have made the new, young imperial characters the protagonists, as highly sympathetic idealists with a genuine commitment to the ideals of the Empire and a character arc similar to the heroes of A New Hope. And I would have put Luke and Han and Leia in situations where they have to commit mass murder to save the Republic.

Then I would have had a final confrontation where the protagonist (now on his way to becoming a young Sith Lord, with a red lightsaber and everything) confronts Luke and accuses him of being a hypocrite no better than Darth Vader. Luke toys with him, delivers the line, "No, there is one great difference: We won." - and then kills him. Then all his friends in the pro-imperial uprising also die.

The ending scene would be another medal-awarding ceremony set up exactly like the one at the end of A New Hope, except this time it's Supreme Chancellor Organa awarding Admiral Solo and Grand Master Skywalker for their excellent work in liquidating the uprising, in front of a huge crowd of faceless, uniformed Republic soldiers. They all hail in unison.
And the musical score would have recognizable elements from the Imperial March.

I'd call it STAR WARS: THE DARK SIDE

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What about The Last Jedi?

I'll post my thoughts about that later.