Regarding Lukaku or Morata dilemmas, if there is such a thing, both rely a lot on explosiveness. Not sure who is going to diminish his first, but the difference is that Lukaku is a better finisher (with his foot) and takes up more space to play with his back to goal, even if he's not very capable of doing much but Morata is far more useful without the ball and can do more with it.
Cost wise it seems to be a significant difference.
I think the difference is how the team responds to each player. Lukaku is more egotistical but will score more. And he guarantees PK conversions. Morata on the other hand will have the same bad misses as Lukaku, less goals, but he will probably allow the team to create more chances and give his teammates more room for goals.
And at least Morata scores in big games.
If we're between the two, I'm leaning Morata only because we have Frattesi, Barella and two wing backs who can score, but both options are subpar given the cost.