Both Mulcair and Rae were my personal first pick for leader of their respective parties. Both are smart, prepared, experienced, and responsible. Both are pragmatic progressives, and that's the sort of politics I support.
Just looking at the leaders, you might wonder what the difference is between the NDP and Liberals at this point. I think the differences are still there, but the differences are mostly in the members and supporters of the two parties.
The NDP continues to be much more ideological than the Liberals. It represents unions and other interest groups; it is truly the Left. The party is largely made up of activists, unions, students and academics.
The Liberals, on the other hand, continue to be a Centrist party in that they stand for good governance above everything else. The Liberals are all about finding a balance between fiscal responsibility and progressive social policies. The membership crosses all boundaries. (And currently, being the party of good governance with 20% popular support is sort of a sad situation.)
I support the Liberals because I think they form the best governments. I used to support the NDP (and continue to like the party) because they generate great policies. I supported Mulcair not just because I liked him best but because - for the first time - the NDP has a chance of forming a federal government, and he was the only candidate who is qualified for that eventuality.
I'm still of a mind that both parties have a place in Canada and we'd be worse off if they merged - but I'm starting to waver. In any event, the leadership has become so similar that I don't see how either party can compete in an election without some sort of cooperation. The big question is how to do that, and luckily we have some time to sort it out before the next election.