I know you're nervous and you want to be extra careful but, really, it's fine. All servers fulfill AirVPN's requirements on privacy and technology. If an US server is by geographic distance and/or latency the "best" for you, use it.
Define "riskier". All connections are encrypted. Sometimes people may quote a benefit of connecting to servers outside the country you're in. In my humble opinion it's a recommendation based way too much on what feels secure rather than what actually is, and a false sense of security is much worse than no security at all.