- Like what you've got: Reconsider. Yes, these cameras are fine up to a point (typically 11x14" prints and ISO 1600). But there's a very much improved camera awaiting you in the D500.
- Dislike what you've got: get a D500. The introduction of the D500 finally gives us a real update for the D300 models, and one that, as the number suggests, probably skips a generation in terms of overall performance (remember my basic advice: buy every other generation as an upgrade). You lose an internal flash but gain Wi-Fi, but the real change is in sensor and autofocus performance, which is exactly where you want big gains.
- Upgrade to mirrorless: Z50II, but you’ll be dropping in body quality.