To me, there is no argument for thinking Jones is going to be Buckner, or that Jones is 'ascending' and Payne is not. Jones is older than Payne. Payne is simply a better player and a much lower risk investment.
Jones is and always been a feast or famine player. He's unlikely to be a great run defender because he weighs like 285 lbs and simply doesn't have the game to be consistently good against the run. He is way less versatile than Payne, really unable to play 2 gap effectively from my viewing of him.
Even assuming he's going to be Grady Jarrett is a huge jump imo. I'd say that with how thin the Bears are at DL, I'd prefer paying more a guy who is much more likely to be very impactful, and certainly is more of an anchor.
There's more to whether a player is ascending or not than age. Sure, Payne is a few months younger than Jones, but Payne has also played 5 years to Jones' 4. More importantly, Payne has played almost twice as many snaps (4180) and Jones (2176). This is also the first year Jones has played more than 63% of his team's snaps while Payne has played 75%+ in all but 1 year where he missed the only game of his career. I'm not saying that Payne isn't ascending. I'm saying we've seen him on the field enough to know more of what he is. And he may be worth the money it takes to sign him, but he'll never give you a surplus value because he's going to get paid as the 2nd best DT in the league and he'll never be more than that as long as Donald is around.
I agree with your assessment of Jones. I'm not arguing that Jones is better than Payne in anyway. But Jones has also been a 3-4DE, not a 4-3 three-technique. Granted, he plays the 3T in nickel the majority of the time, but that, to me, is another area where you can see some ascension from Jones in the base D.
And I wasn't assuming he'd be Grady Jarrett. Just saying IF he can be that, he gives you surplus value for what his contract is likely to be. Because he may be the 10th highest paid DT, but he could give you top 5 performance.
Again, I'm not arguing that I prefer Jones over Payne. I'm arguing that Poles may, and I'm explaining why. You don't have to prove to me that Payne is a better player, because I know that. Everyone knows that, that's why the price tags will be vastly different in free agency. Point is, what are you willing to pay for that difference, is all.