I think it's worth noting that the United States has 3x as many murders per capita per year as compared to Canada. I'd hate to see American-style justice come to Canada, because it clearly doesn't keep the country safe.
Arguably, the best country to murder someone (as in, get away with it) would be any dictatorship where you are one of the thugs employed by the murderous regime, with the task of making people "disappear".
Also, in any country in which the justice system is broken, you can murder people and get away with it by getting a job as an executioner. What your state considers a lawful execution is regarded as murder in the eyes of the sane world, and so you're getting away with murder.
In Canada, you can kill someone and get only six years.
http://www.cbc.ca/news/canada/edmonton/killer-of-thai-welder...
http://www.cbc.ca/news/canada/glowatski-sentenced-to-six-yea...
http://www.cbc.ca/news/canada/saskatchewan/northern-sask-man...
http://www.cbc.ca/news/canada/newfoundland-labrador/kenny-gr...
http://www.cbc.ca/news/canada/new-brunswick/ryan-hickey-sent...