Wildcat has mystically decelerated aging though, so he's only "old" in the same sense that someone like Captain America is (not quite the same obviously but close enough - he's been around for years but his physical body is that of a far younger man).
Dredd genuinely ages in real time and has no decelerated aging (although average life spans are slightly higher in the Dredd-verse thanks to medical tech). He's in his early 70s now and has all of the negatives that carries with it (his physical speed and strength are explicitly drastically lower than they used to be; he's even been diagnosed with arthritis and a form of cancer). Despite that, he's still vastly more active on a day-to-day basis than any of the others on the list (even bog-standard Judges routinely work the streets for 20 hours a day or more, 365 days a year - and Dredd routinely goes way beyond that).
In terms of physical toughness, Dredd's damage soak feats are superior to Castle's IMHO based on an extensive reading of both, although both are ridiculous. He's walked off having all of his skin and most of his flesh burnt off, nose completely gone, the works (and unlike Wolverine, he doesn't have accelerated healing to deal with that kind of injury). Shrugged off being crucified for days and shot twice point blank in the gut during the crucifixion etc.
In terms of mental toughness, I always think back to 2000AD #863, which had a guy steal "a handful" of Dredd's memories and artificially implant them into his own brain. That small sample of the things Dredd had experienced caused the guy's head to quite literally explode. He's also far less prone to mental/emotional breakdowns than Castle or Wolverine. He is also much cooler under pressure than either of those two IMHO (not in the sense that he functions better necessarily, just in the sense that he is far more emotionally understated than either, colder, more calculating - he doesn't succumb to rage or guilt or whatever, he is just about always 100% logical/rational to an almost robotic extent).
Cheers.