It’s exactly as the title says, what is your favorite part of the dc universe being a shared universe.
For me it’s when character and story elements come together
-It’s when Scarecrow harnesses Yellow Lantern Power so Batman needs the Green Lanterns
-It’s when in Batman/Superman Gordon falls down his old Batman mech to help in a fight
-It’s when the Wonder Twins can intern at the hall of justice
-It’s when Hawkman travels through time and space to see his origin, including Krypton
-It’s when we see other heroes helping out in the background of Justice League.
That’s a short list but I think you get the idea.
So what’s your favorite part of having a shared universe. Feel free to give examples.