We're only on iOS at the moment, building for android, and soft launched a few weeks ago.
With PR, it should always be about finding people who are genuinely interested / excited about what you're doing, so I would suggest targeting those people regardless of whether they are nice, hyper-local, or broad. Leave no stone unturned but it really depends on what you can use as a hook, which without understanding where you're exactly at, can't help beyond this general advice.
One thing I'd add as a note of caution is that if you're not already trending towards 100,000 installs since US app store availability, it's going to be very difficult to get press coverage absent a very unique hook.
Happy to talk to you to try and help identify what hooks you might have.
Best of luck!