Toronto's biggest such area would be the Yonge Street strip, especially the corner of Yonge and Dundas, which has dozens of massive advertisements and huge video screens looking over the streets and the plaza.
Chinatown would be another area. There are lots of neon signs (there are many restaurants open until 4am or later 7 nights a week), and a large video screen at the corner of Spadina and Dundas.
Yonge + Eglinton would be another area, especially with the Yonge-Eglinton Centre and Canada Square.
North York City Centre would sort of qualify - around Empress Walk. The corner of Yonge + Sheppard will be another such major intersection with huge colourful signs and bright lights when the Hullmark Centre is complete, combined with the existing Yonge-Sheppard Centre.
When 1 Bloor East if finished Yonge + Bloor will likely be another such area.
What I don't like about these neon districts in Los Angeles and Toronto is that they're artificial and built with the sole purpose to serve as a Times Square like area. Times Square, Ginza, Shibuya, etc on the other hand are organic and developed over time in what was already a busy intersection of the city.
Wrong. Toronto's Yonge Street strip also developed over many decades and has been Canada's busiest intersection for many decades. It was not artificially built to be a Times Square like area. If had massive advertisements and large, colourful signs 60+ years ago. It wasn't entirely built up recently.