Jones: 24 (by their fight)
Rampage is on the wrong side of 30, Jones is clearly in his prime and may not have even hit his peak yet. However this can be taken a step farther:
When you look at it from that perspective suddenly 33 seems a lot older. It may not be the Randy Couture 47, but Randy is no ordinary man and he didn't make his MMA debut until he was 34. His career spanned 13 years, only one more than Rampage.... It's worth noting that Jones and Rampage both starter their careers at almost the same age, however the mileage that Rampage has put on his body is dramatic compared to what Jones has gone through.
This is literally a match up of the shortest against the longest reach in the division. Rampage is a great striker, he's overcome a deficit to knock out some of the best, Liddell, Jardine (maybe not the best...) he landed a solid one on Rashad and he even tagged the elusive Machida.
But Jon Jones is practically Dhalsim from Street Fighter and he nearly has a foot in reach in his favour. Once again
3) Fights or "Fight IQ"
Rampage: 40 (32-8)
Jones: 14 (13-1)
Really I think this whole "Fight IQ" people seem to bring up when measuring great fighters seems a little ridiculous but I'm not sure what else to call it and that seems to be the accepted nomenclature. To cut it short, no one has had anything for Jon Jones. Not his loss over Matt Hamill which was really a win that he won too badly and he was disqualified for winning in too brutal a fashion... not Stephan Bonnar when a wikipedia viewer will say "Hey he took him the distance!" it was not pretty, it wasn't a moral victory like Rocky, it was a brutal beating and fills a highlight reel... and not even Shogun put Jones in any sort of danger.
So it is almost debatable, if not even the #1 (at the time) LHW could give Jones trouble wouldn't that say a clear victory is ahead of him? I think you could make that case. But I think you could also see that Rampage has fought the best of the best for almost his entire career. He's fought almost every LHW worth mentioning, so maybe his experience can aid him. He's been in put in danger and powered through rough spots where a lesser man would've done the stanky leg and crumpled to the canvas... maybe he will be the first man to land his vicious left hook on Jones chin, maybe he'll put Jones in "deep water" where he's never been, maybe he can break Jon Jones will.
Regardless, my title has given away my true feelings on the fight. Rampage is fighting an uphill battle here. Making weight, keeping up cardio for what very well could be a 5 round fight, overcoming years of injuries, mentally preparing for what is most likely the toughest fight of your career when you're already thinking about how close retirement could be... These are all really working against him.
I wouldn't count him out yet. Miracles have happened, we didn't get to see one through Randy or Chuck, but Tito Ortiz showed that maybe the old guard isn't quite dead yet. So here's hoping Rampage can beat the numbers.