While the Regeneratin' Degenerate known as Deadpool is famous for his overactive healing factor, he managed to upgrade it even further by hooking up with Weapon X - the organization that created Wolverine. Deadpool's healing factor is unique, having merged with his cancer so that Wade regenerates damaged body parts with dead tissue and therefore needs this power to live. However, when taken to the next level, Wade's healing factor didn't just heal damage - it built him back better.
Deadpool was initially conceived based on Danny DeVito's role in Twins, with the idea that he was the Weapon X reject who paled in comparison to Wolverine's unqualified success. Ultimately, the Merc with the Mouth became a fan-favorite hero, and in modern stories, his healing outshines even that of Wolverine, with Wade able to survive incredible injury, from decapitation to incineration. It's been confirmed that he'd need to be disassembled at the molecular level to stand even a chance of staying dead.
However, Wade's healing was once even more impressive. In 1997's Deadpool #57 - from Frank Tieri and Georges Jeanty - Deadpool is recruited by a revitalized Weapon X. After undergoing fresh experimentation, his healing factor is drastically improved. Most important to Wade, it is apparently uncoupled from his cancer, meaning that his ever-shifting tumors subside and he returns to the appearance he had before his original powers drastically damaged his skin. Deadpool is also able to regenerate limbs even faster, consciously control his healing, and - best of all - whatever he regrows actually comes back better than when it was damaged.
It's suggested Wade's regenerated limbs are stronger and more durable, and could even deflect bullets. This enhanced strength is significant, as Sabretooth - who's been subjected to similar upgrades - is able to throw Deadpool across a room with a single hand. Being able to control his healing also gives Wade a tactical advantage similar to Deathstroke - the DC character rumored to have originally inspired his creation. Voluntary healing allows Deadpool to play possum, as well as to employ his healing factor creatively - e.g. by 'pruning' himself to slip through tiny gaps. However, the most obvious advantage is that every time Deadpool loses a body part, he knows the replacement will come back even better - an advantage anyone who frequently tangles with Wolverine's claws can use. Sadly, Deadpool was forced to sacrifice these abilities when he ultimately turned against Weapon X.
This version of Deadpool's amped-up healing is comparable to his daughter Ellie's. Ellie is able to 'reboot' her body, returning to the age and condition she was when her powers first manifested. This means Ellie can die as an old woman and spring back to life in her prime, though even she isn't able to enhance herself beyond this 'base' form. Arguably, Deadpool should make it a priority to force Weapon X to recreate his upgraded healing, as the current version has been shown to be able to kill - or even zombify - those who are infected by his blood.
While Deadpool's healing makes him near impossible to kill, it comes with a laundry list of downsides that harm his own quality of life and risk some major consequences if misused. With his upgraded Weapon X healing, Deadpool had all the advantages and none of the drawbacks, as well as the knowledge that he wasn't just healing, but constantly improving - a power even Wolverine would be jealous of.