Since language retention is often reflective of keeping customs alive, I wonder how Buffalo's Polish community does in that regard.
Toronto has over 33,000 Polish speakers in the 2011 NHS, and
based on this while the city of Chicago itself has over 80 000, the Metro area itself has around 182, 000 speakers.
So we've got 182 000 language speakers, compared to 139 000 Polish immigrants in Metro Chicago, while there's 33, 000 Polish language speakers compared to 24 000 Polish immigrants in Toronto. So in general, the percentage of language speakers who are immigrants vs. native born seems to be not too far off. So both cities probably didn't differ too much in how much the language was passed on to the second and later generations.
Despite Chicago and Toronto both being major destinations for the post-Soviet wave of Polish immigrants, Chicago's Polish immigrants still make up a lower proportion (about 15%) of the total claiming Polish ancestry in the city and its surroundings (over 900,000 or close to a million) than Toronto which has more like 100,000 with Polish roots but a quarter are immigrants.
As to Buffalo, I'm not sure where to find stats. New York state as a whole has about 95, 000 language speakers but probably a lot of that is NYC itself, and I'm not sure how many Polish Buffalonians speak the language.