NDP = A good opposition party, but no one in their right mind would ever want them leading the country.
and the rest are too small or single(-issue) focused to matter.
I told him in my response that I had issues with that characterization. But at the time, I didn't have the time to answer them properly.
First off, regarding the NDP: the experience of several million Canadians of particular age ranges who've lived - or are living now - in provinces governed by that party is strong evidence to the contrary of that assertion. Granted that not all such Canadians voted for that party if they voted at all in those provincial elections, but they do have experience of competent governance by their local arm of the NDP. I count myself among them, having grown up in Saskatchewan during the Blakeney years.
Further, I realize a lot of my fellow Ontarians take issue with that, citing Bob Rae's term in office. Countering that, I'd point to the overreaction to several of the decisions taken by him and his team whilst in office leading directly to the misrule we experienced under Mike Harris' Conservatives for the better part of the next decade. And given that some of Harris' most trusted cabinet members are now in similar roles in the Harper Government at the federal level, the entire nation is dealing with more consequences of those Ontarian choices.
As to the Greens, a careful perusal of their blogs - particular attention to Elizabeth May should be paid here! - will disabuse most rational voters of the charge of single-issue obsession.
I can't yet pay closer attention to the rest of the federal parties not currently in the House, but hope to do so at some near future point.