I asked a question earlier which I tagged emulation. Another user posted a question tagged emulator. Which is the preferred, and should I go ahead and retag whichever question turns out to be using the "non-preferred?"
I don't think there's a strong enough distinction between questions about emulation and questions about emulators to warrant keeping two separate tags.
To that end, a question that is about emulation is not necessarily about emulators themselves, but all questions about emulators themselves are about emulation. So I would suggest [emulation].
I don't see the harm in both. Emulation is the general topic ("what software is best for Amiga emulation?"), whereas an emulator could be talking about a specific bit of software ("How do I configure DOSBox for X-Wing vs TIE Fighter?").