Having looked at several North American metros, here's a listing of immigrant populations (of at least 5000) where Toronto is in the top 3.
#1:
United Kingdom 116,655
Sri Lanka 105,565
Pakistan 99,295
Hong Kong 99,285
Portugal 73,740
Romania 24,515
Afghanistan 21,185
South Africa 13,575
Serbia 13,505
Croatia 13,175
Kenya 11,240
Bosnia and Herzegovina 10,090
Netherlands 9,765
Saudi Arabia 8,105
#2:
India 279,425 (New York is #1)
China 237,025 (New York)*
Philippines 185,085 (Los Angeles)*
Italy 116,240 (New York)
Guyana 72,090 (New York)
Iran 60,785 (Los Angeles)
Trinidad and Tobago 46,915 (New York)
Russia 35,200 (New York)
Ukraine 31,795 (New York)
Greece 31,185 (New York)
Germany 27,635 (New York)
Bangladesh 25,560 (New York)
Iraq 22,145 (Detroit)
Hungary 14,725 (New York)
Turkey 11,125 (New York)
Albania 10,010 (New York)
Czechoslovakia 9,365 (New York)
Barbados 8,305 (New York)
St. Vincent/Grenadines 7,835 (New York)
Malaysia 7,690 (New York)
Grenada 7,565 (New York)
Macedonia 6,410 (New York)
Belarus 5,540 (New York)
#3:
Jamaica 97,660 (New York, Miami)
Poland 64,095 (Chicago, New York)
Ghana 14,035 (New York, Washington)
Israel 13,440 (New York, Los Angeles)
Ireland 9,715 (New York, Boston)
Bulgaria 6,905 (Chicago, New York)
Syria 5,245 (New York, Los Angeles)
* The Bay Area is split into San Francisco-Oakland and San Jose MSAs; if they are combined Toronto is #3 behind the Bay Area.