I'll add a couple other Canadians - Stephen Fearing, and Heather Bishop.
Bruce Cockburn has produced a staggering number of great songs. He is still going strong. I think it would be difficult to dispute that BC is in the midst of one of the greatest singer/songwriter careers in the folk/rock genre. Time will tell. This statement is not intended to take anything from all the other great songwriters, past and present. I just don't think that BC has received the credit he has earned, and his career is still developing.
Be well,
JK