I would like 616's Peter meeting her counterpart in the Ultimate Universe, honestly.
And personally, there's one plot I would like to be solved in this reality but that was practically forgotten: Mary Jane injected with the OZ formula. She was turned into the Ultimate DemoGoblin, apparently cured by Reed Richards, but then there were clues hitting the curee may not be complete.
Ultimate Jessica Drew gives me some doubts. She technically is a mix between Jessica Drew AND Ben Reilly, but right now, there's another potential/possible counterpart for her: Teresa Parker, the "undecided" sister of Peter Parker.