I don't want to seem biased, but I suppose I haven't witnessed any systems outside of North America & the Caribbean, and I've only WORKED for Canada.
But I believe that Canada provides EMS providers with ample job opportunities, advancement, adequate pay, and significant freedom to practice within protocols, as well as respectable protection in the case of lawsuit or litigation. Also, with the variety of jobs you can take as an EMT/Medic in Canada, its hard to be bored. Personally, I have worked urban/rural, oil & gas, music festivals, hockey & football games, rodeos, and hopefully the Olympics next year in Vancouver.
Combining these aspects, and the increasing ability of medics to transfer across provincial boundaries (a work in progress, but going in the right direction overall), I think that Canada is a great place to work for EMS.