Toronto (Markham) and Quebec City. The new Toronto would be placed in the Central Conference (league would be 4 conferences of two divisions each) and Columbus most likely moving to the Atlantic Conference.
That ensures every team plays a Toronto team 4 times in a season and comes into Toronto twice helping to boost canadian tv value. It also placates the Leafs as the new team doesn't become a direct on oce competitor being in a different conference and perserves to Boston-Montreal rivalry. If bith teams were placed in the Northeast then Boston would have to be moved to the Atlantic killing that rivalry. Also putting the new Toronto team in the central gives Winnipeg a canadian buddy in that conference.