Dzeko has more experience but he is far older compared with lukaku. That depends on what kind of strategy that will be used by simeone. If the club will be focusing to the counter attack strategy and im thinking if lukaku is far more reliable compared with dzeko.
Dzeko may become stand alone striker. Lukaku will give more benefits for intermilan caused by he was able helping its team by taking multiple role.
Lukaku has speed and great physic like haaland or even better. I prefer to take lukaku since the first half rather than dzeko.
Lukaku would be better to put upfront. he can fight with his physical strength to fight against the opponent's defense. moreover, Man City has a game character that will carry out fast attacks. and there will be a loose line of defense, Lukaku can get chances with his pace.
if you want to play both at the same time, maybe it's a gamble for Inter. it would be better for Dzeko to be a substitute to anticipate a situation that might be difficult for Inter with pressure from Man City.