Chris Paul
He is better by box-score and plus-minus career value metrics.
CP3
VORP-108.83 (6th all-time)
WS-229.13 (8th)
Harden
VORP-91.17 (15th all-time)
WS-185.68 (24 th all-time)
Keep in mind, CP3 stands out even more in per-possession impact. His playoff career value is hurt by some shorter playoff stints.
Looking at long-term RAPM, CP3 comes out superior.
97-2024 Englemann RAPM (No age adjustment)
CP3: +9 (3rd)
Harden: +6.3 (21st)
If you look at RAPM that adjusts for age, the gap growths a bit.
97-2024 Englemann RAPM
CP3: +9.4 (3rd)
Harden: +6.4 (24th)
CP3 is having more per-possession impact over several more possessions so far in his career. Harden would have to have an unusual age curve to catch CP3 by the same age, or (more realistic), have special longevity to pass Paul, despite weaker per-possession impact.
CP3's playmaking, defense, and general turnover economy over a number of years matters.
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In my estimation, Harden's PS play hasn't been at CP3's level either. The only thing you could maybe dock CP3 for is his durability in some PS runs. If you don't think they are flukey injuries, and you really believe CP3 would be incapable of playing close to the same level through a whole championship run, then Harden makes up ground.
Though CP3 faced historically difficult defenses in his prime, and improved from the RS to the PS. So its not like Paul wasn't challenged but would be based more on the belief that CP3's play would fall off a clip against weaker defenses, in a vacuum, do to his physical shortcomings.
And while Harden made deeper playoff runs, Paul faced some historic PS defenses. From 12-16, CP3 some of the faced the toughest defenses ever of any superstar by rDRTG in a 5-year span, facing an average D of -2.61 (12-16) just barely behind Karl Malone for 3rd place of the toughest defenses ever faced for notable superstars
https://diamondhoop5.wordpress.com/2021/07/12/playoff-defenses-faced-update/.
Not only did CP3 not necessarily get to boost his playoff numbers against bad defenses, but he looks this insane going up great ones and gives the imprint of a guy who is an all-timer who ran up against some tough teams. Paul's team offenses haven been great, posting a playoff offensive relative efficiency of +5.7 from 2013-17 and a 3-year offensive peak of 7.7 (15-17). Though even if you adjust for Harden's defenses be tougher, there is nothing that suggests he would be at the same level of play as Paul. Paul's team offensive profile has been better by my estimation.
All-in-all:
Chris Paul's PS Peaks
3-year Backpicks BPM-7.4
5-year BPM-9.60
3-year PS On/Off-14.7
CP3 also has a higher 3-year peak in the PS xgboost model predicting LEBRON created by one of the developers of the LEBRON metric (box-score only though)
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Harden's PS Peaks
3-year Backpicks BPM-7.3
5-year BPM-8.3
3-year Peak LEBRON-5.28
I don't believe it egregious to give Paul the edge over Harden when you consider that CP3's prime was longer and statistically his playoff peak looks so abnormally good. The longevity is impressive. The longevity is impressive. For instance, Paul has the 2nd most postseason runs over +4 in AuPM per game since 1997 with 7 (behind Lebron), so he has shown great consistency. Keep in mind a +4 is around the area of what you would expect for a top 5 guy, so that is significant added value.