Visa Free Transit in Shanghai, or use my Q2 type

Hello, I will be flying into Shanghai from Canada, and then after two days I will be flying from Shanghai to Tokyo. In addition, I already have a multiple entry Q2 type in my passport. The question I have is when I enter Shanghai, should I be using the 144h Free Transit counter or the regular immigration counter with my Q2 type? My sole purpose in Shanghai this time is solely for transit, and I won't be visiting any relatives. If Free Transit, should I also inform the airline when I check in? Any comments are highly appreciated.
Sandy