I think the N1 and the incredible are basically identical.
People claiming more smoothness might just be seeing some better animations in the Sense UI implemented by HTC.
Here is how I see it: Hardware-wise, the difference is
N1 has a bigger battery but the trackball.
The Incredible has a smaller battery but an optical trackpad and a better camera and some internal storage.
Sofware-wise
the Incredible has sense UI which can be an improvement
The N1 is anointed by google. Meaning 1st shot at updates directly from google and the root makes it so you can EASILY add sense or anything else you want.
The big determinant here is price. The incredible will likely be eligible for NE2 and may even have a lower price.
The N1 made sense for T-mobile where if you buy your phone out right there are special low priced plans that reflect the fact that there is no subsidy.
Verizon doesn't have this.
As for screen, it will be the SAME screen. The two phones are basically identical, they won't re-engineer the screen.
The camera doesn't make too much of a difference. If you know anything about photography, past a certain point, its sensor size and lens that makes more of a difference than megapixel. The N1 takes excellent pictures and video compared to the droid for example.
Lets see what comes out first and what pricing we'll get. I think either phone will make you happy.