Skip Brampton. It is garbage. Other points of interest not mentioned...
Casa Loma, Fort York, Distillery District, ROM, AGO, Chinatown, High Park, Mirvish Musical, Skating at Nathan Phillips Square or at the Bentway.
For food the Winterlicious festival might be on when you’re here so you could look into that also there is a new food hall called Chef’s Assembly Hall. Definitely get some street meat, it’s excellent in Toronto.
For a day trip getaway in addition to Niagara Falls you might want at Collingwoid. It’s a big ski area north of Toronto but has a nice little town and winter activities.