Whats the view on a new Dial, if it's brand new, NOS, in its original Omega packaging (to put on a watch I buy)?
I believe you mean VS the original dial. It depends on several factors, whether it is real NOS vs "New New Omega" stock or really old (as the original. How degraded is the original, whether it matches the type that went on that watch, and I am sure others will give you other considerations.
If one had to state a pecking order, I would suggest: 1. The original dial 2. A replacement, period dial 3. A new NOS period dial 4. A manufacturer's current, replacement dial 5. A replacement dial that is refinished. 6. Refinished the original dial The caveat would be that 4. to 6. would be a last resort and for 2. to 5, keep the original dial to pass onto the next owner. The other thing to consider is how the hands would look with options 3 to 6 - you could pretty much repeat the same list for hands.
If a watch doesn't have a mint original dial (as in the dial that came on the watch from the factory) my next choice would be a NOS identical replacement dial or a refinish of the original dial by the factory to original specifications (as in exact fonts and inking). If it isn't a collectable model and I want it as a daily driver, then a more recent factory replacement dial will suffice. After being burnt on poor to mediocre redials as a n00b, I can't bring myself to buy one now.
For collecting only I agree with leaving and perhaps a gentle clean done by a professional. With a daily wearer, I'd be more likely to succumb to the temptation of changing, but only for a NOS or as you say factory fitted dial. There are some watches out there where the condition of the dial is truly horrendous, but the mechanism appears to look ok. These are the ones I can currently afford to get, so condition of the dial is secondary. However, I fully agree with all of the comments and as a relatively new owner/collecter take them on board. Thanks all.
You may think you will love that perfect dial but sometimes you just can't seem to let that old one go.