There's no such thing as a perfect system. but I'll go with the one that has killed humans the least.
Communism looks good on paper, but in reality, it killed roughly 60 million people all over the world per year (though this has petered out as it gets less popular in most countries save for places like Korea).
Fascism is a close second in most people killed per year, though like Commuism it peters out due to it becoming less popular in modern times.
Under those two systems, they deliberately engage in genocide and mass killings.
Capitalist crimes on the other hand-- modern-day deaths are very rare, and mainly due to poor people not being able to afford things like food, heat, etc.
it is definitely guilty for past historical crimes on the other hand, such as the death of slaves due to American greed and things like that. But nowadays the deaths are mainly to failures in the system, rather than an intentional death to satisfy the ideology.
But. we're getting off-topic. is there a thread where we could discuss this instead?