I'm from cali. unless you from ny they both might as well be fictional. if we keeping it real I'm more familiar with Gotham than ny.You're not following.
Setting it in even fictional NYC has context already built in,that was 42nd st. and Park Ave. where the final main battle occurred in Avengers, Hell's Kitchen is a real place, with a history. The Hulk and Abomination fight and the Luke Cage series will be in Harlem also a real place,with a real history etc. Metropolis has no such real world context, therefore it can't be more realistic.