Apples and oranges. Consider this report: http://www.cnn.com/2013/04/10/world/amnesty-international-de...
In 2012, the US executed 43 people. The number of executions in China? Believed to be in the thousands.
How did the condemned in the United States die? Here's the breakdown: http://www.deathpenaltyinfo.org/methods-execution . Note that all of these individuals were afforded appeals and legal representation.
Some of the other countries? Maybe no trial at all. Maybe a completely rigged trial. Appeals? Doubtful but short. Time between being charged with the crime and execution? Perhaps days, as opposed to years in the United States. The method of execution? Anything goes; in North Korea the Kim regime has become especially creative here, dropping mortars and using AA guns to kill prisoners.
Is the U.S. justice system faulty? Yes. Can one make a compelling argument against the death penalty? Probably. Can an honest argument be made that the United States and China (let alone some of the other countries on the list) are even in the same league? Doubtful.