The 24-120 is a better lens, but none of Nikon's lenses - even the cheap kit lenses - are easily dismissed. You can probably find differences if you pixel peep, but likely not much of a difference in a small print such as an 11x14.
What you will see is a big difference in wide angle capability. 24 and 18 are not very similar in wide angle - on your 5dmk3, that's the difference between 28 and 35.
I think you'll also find that there is a considerable difference in weight and bulk. The 24-120/f4 weighs 720g and takes a 77mm filter, while the 18-105 weighs 410 and takes a 67mm. Considering that you're switching not just cameras but camera systems because your previous model was "a brick" I'd guess that this is important to you.
In short, my advice is to go for the 18-105.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!