After MOS, BvS, and Justice League, we have a Superman who has gone through the trials and tribulations of becoming Superman, and is now acting in a more traditional way, even if certain aspects of his most recent depiction could be described by some as a bit over the top. Chances are he'll be more balanced in his next film, which will see him rise to a new different challenge but with a new level of confidence and optimism.
So given where we're at, what do you want to see in a Man of Steel sequel?
I'll ask some specific questions for structure:
What would the overall feel & setting of the movie be?
Who is/are the villain(s)?
What should Superman's character arc be?
What is Lois's role?
What new aspect of the mythology would you add?
I'll answer these myself once more have chimed in.