When it comes to healing factors in the Marvel universe fans always think of Wolverine, but there's another Avenger whose healing abilities make Wolverine look weak. That's because he heals using energy rather than his own flesh and blood. This, of course, is European sensation Simon Williams, Wonder Man.
First created by Stan Lee and Jack Kirby in Avengers #9, Simon Williams was a young businessman in charge of his father's company. After being arrested for embezzlement because of his brother, Simon blamed his competitor, Tony Stark, for his downfall. Sensing an opportunity, Baron Zemo recruited Williams and gave him powers in order to fight the Avengers as the newly dubbed Wonder Man. Fortunately, Williams had a crisis of consciousness and actually helped the Avengers defeat their deadliest foes, the Masters of Evil, solidifying his place as a hero rather than a villain.
Wonder Man's powers are energy-based, essentially turning his whole body into an ionic battery. This goes so far that Simon has no blood in his body and is infertile. Interestingly, this also prevents him from bonding with symbiotes as he technically isn’t an organism. Having control over this energy allows him to heal in absolutely ridiculous ways. In fact, the process that gave him superpowers made him virtually immortal. He's died several times and has come back to life, even going so far as to scatter his body into energy particles before reconstituting himself.
While Wolverine’s healing is impressive, Logan will always have a disadvantage compared to Wonder Man who simply heals through energy. Both of the heroes’ aging is affected by this process as well. But while Logan simply ages at an incredibly slow rate, it’s possible that Wonder Man doesn’t age at all. It’s inferred that Simon lives far into the future when a version of him called Hollywood interacts with the Guardians of the Galaxy. Even more than that, Wolverine can technically die, and he has in many different incarnations. Notably, the powerful sentinel Nimrod was able to obliterate Wolverine's entire body with an energy blast.
While Wolverine can heal from extraordinary injuries, he still needs a body to actually do the healing. If that body is completely wiped out then it would be unable to stitch itself back together. Since the Avengers' Wonder Man is constructed of energy he doesn't have the same handicap that Wolverine's healing does in this manner.