The killer

The doctor just keeps the amount of killers higher

military hospital doc versus special forces... Doc's more effective.

Treating people can be a process depending on what ails them, Killing is a rather quick thing.

Depends on who encounters more violent individuals right? I guess they both have demoted themselves to middle management and depend on the performance of others

Depends on how methodical the killer is.

If they get caught the doctor wins, basically full stop.

Sounds vaguely like the plot of monster. Great anime. https://www.anime-planet.com/anime/monster

What if the doctor also saves the killer from prison?

Turns out it's just one killer they both keep attacking and reviving.

Depends on the killers the killer kills.

On an unrelated note, vaccinations save millions of lives every year.

Oh yeah, then there is this -> https://www.cgdev.org/blog/update-lives-lost-usaid-cuts

Unnecessary plot twist:

The doctor is the killer!!! 😱😈😑

The doctor would kill more people and the Serial killer killer would save more.

Each serial killer would have most likely gone on to kill more than 1 person, so the doctor would be responsible for more deaths.

Second would save more

Yes exactly. I don't understand the question, how is it even a competition?

For instance: If the killers are killers for killing only one person and are killed by the metakiller after the fact. The doctor is saving lives while the killer is just adding kills without reducing the number of kills at any point.

As a general rule: Under the assumption that killers would not kill again after being declared killers then the doctor will always save more lives than the metakiller.

It depends on how many people the killers would kill after their iteration with the doctor or the metakiller.

To the number of total future victims you add the number of killers for the metakiller. Then to the number of total future victims you rest the number of killers for the doctor. You compare both numbers, the smallest number win.