Baltimore.
Both feature one or two locally-beloved sports teams, both are located on each country's main urban corridor. Has a dense, urban, but single-family oriented vernacular housng stock. Both cities have somewhat-overlooked cultural institutions, and both have leading medical universities. Both had major steel and port facilities, both gritty, but with interesting natural features within them. Baltimore is attractive to residents seeking an alternative to Washington, as Hamilton is to Toronto. Both cities have two separate downtown commuter rail stations connecting to Washington/Toronto.
Baltimore has a somewhat vibrant downtown, especially the Inner Harbour. Hamilton's downtown is being renewed, but there are areas just outside of it, especially to the east, which are quite poor and won't be seeing gentrification anytime soon.