If you could choose noise reduction or ADR. What would you choose? (Poll)
That all depends on the actor and their performance.
Noise reduction if the actor's performance on set is excellent and the dialog isn't too far gone.
ADR if the actor's performance is fair but needs some help. Perhaps they can nail it in the studio.
It's a Catch-22 if the actor is bad. They probably can't perform any better in the studio than they did on the set (probably worse considering they're paying attention to sync and not in the moment anymore); on the other hand, why go to great lengths to clean up traffic noise out of a bad performance.
I'd choose noise reduction every time, provided you have the appropriate tools available. You can do a lot with just EQ and compression/expansion as well. Admittedly, there are times where you may not be able to avoid ADR. Most of the projects I work on aren't large enough to have ADR as an option to begin with.
Also, never underestimate the power of creative "masking" when dealing with production noises. I had one project where I got rid of nearly everything except for this one narrow band of steady noise. I couldn't take it down any farther without adversely affecting the dialogue in the scene. It wasn't that present, but it was noticeable. I pointed it out to my coworker (who does all of our music composition) and asked him to throw in some sort of drone in that frequency range when he was working on that scene. Once his music was in, there was no perceiving the offending sound.
Noise reduction 90% of the time. As it was said in the above comments, if the performance is bad then yes, ADR but if the performance is good, then it is applicable to try and salvage the dialogue. I find so much ADR sounds boxy and poorly mixed to match the scene creating an obvious problem with all the rest of the sounds inside the scene.