144 hour TWOV

The first route is not eligible because the basic rule of 144 hour visa free transit requires that the immediate points (regardless of their nature) before and after your mainland Chinese destination have to be in two different countries or eligible territories (eligible territories are Hong Kong, Taiwan and Macau). As you can see in your route number 1, your both immediate points are in Hong Kong. So, not eligible.

Your second route is definitely and undeniably eligible for 144 hour visa free transit valid for the entire Guangdong province. You should just have in mind that you will have to obtain a ticket from Guangdong province, being it Shenzhen or Guangzhou to Hong Kong. You can fly, you can take a ferry or a high speed train. The latter is the most convenient by far. So, you will buy your train ticket in advance, even before your departure from Toronto and print it out. You will have that printout at hand, ready to be presented to relevant authorities when they require one to make an insight. Also, you should be aware that you will really have to take exactly that train you have bought your ticket for. Have a nice journey.