- Like what you've got: Reconsider. The D1x was good for its time, but has two issues that keep it from being close enough to state-of-the-art: the missing rows (it's really a 4024x1324 camera), and very poor shadow detail rendering. You're also missing out on a CLS flash.
- Dislike what you've got: Update. On a budget, try a used D2x or D700, maybe a D500 or a new D750. If you've got the dough, get a new D850, or consider moving to mirrorless with a Z7 or Z7 II.