I think it's a little bit of both.
I have a Sigma 24-70mm f/2.8. It lacks any type of OS/VR but yields sharper images than other copies of this same lens. Last summer as I was putting it away in my bag, it slipped and dropped about one-inch into my padded camera bag. Afterwards the AF wasn't working consistently although eventually it began working normally. Prior to that, I was already looking at options in case something happened to it. But the thing is I never found a suitable replacement. I didn't want the size and weight of either Nikon 24-70mm f/2.8 and really wasn't tempted by the Tamron or Sigma lenses that have vibration reduction.
Eventually I started to take a more serious look at the images posted here from the Nikon 24-120mm f/4 VR and decided to give that lens a try. After using it, I have no plans to move back to any 24-70mm f/2.8 lens because this one fulfills all my needs. And my Sigma works fine now although I've not gone back to it since buying this one. This Nikon zoom can focus in the low light situations I shoot although I don't shoot where it's REALLY dark. Had NO issues shooting hand held during my church's candlelight portion of our Christmas Eve service. And I fully expected for the lens to struggle with its AF. But it didn't.
If I need to shoot in really dark situations, I'd either focus manually or switch to one of my f/1.8 primes. The size/weight of the Nikon 24-120mm is about the same as my Sigma 24-70mm f/2.8. The only difference there is my Sigma takes 82mm front filters while the Nikon takes 77mm (and I already had 77mm front filters from other lenses I own).
But everyone has their own personal preferences to fulfill their wants/needs. Good luck with whatever you choose. And if you choose the Tamron, no doubt you will love it. I am looking forward to seeing pics taken with your new gear.