Romero to me looks different class, or at the very least we'll on his way to becoming different class (qualifier just because it's still early). More players at his level that also for the system would make a big difference of course. Anywhere on the pitch really.
I think Davies still doesn't get enough credit for how good he is in this role. Yeah, not at Romero's level, but I honestly think he's good enough for now.
If we're looking at priorities, for me at least. If we can save some money by bringing in a LCB that's more of an understudy at first, but with massive potential that money could be beer spent elsewhere.
If we can afford and attract another Romero level CB and get good targets for other areas definitely go for it. To replace Davies on current form it would have to be a real quality player though.