Something like 20% of Canadians speak French as their first language so as a whole that would probably be the most important.
But even then. If you are in a community that doesn't have a Spanish or French speaking population it really isnt that great or important. If you practice up in Nunavut its going to be way more important to speak Inuit languages than French (or English for that matter). If you practice in the parts of Toronto with large Somalian populations its going to be way more important to speak Somali than anything else.