GiGi is definitely the best pizza in Toronto during the wee hours of the night/morning.
They have fresh toppings and will make you pie before you sober up enough to remember the bite you're about to take is scorching hot (happens every time!)
The slices are decent but if there is more than one o' youz, I would recommend a fresh one made with the toppings of your choice. Worth the trip late night if you're craving pizza.