Of all the slices I've had in Mississauga, the one (shown above) at the San Francesco's (the one located in a plaza at Britannia and Creditview) is BY FAR my favourite. And I know San Francesco's is a chain, but they're independently run - so you can't just go to any to get this great slice. You have to go to this specific location. It's right near my brother Robbie's work, so he was the one who introduced us (us meaning me and this slice). TRY THIS NOW.
If you care to see a recent list of other top slices in the fine city of Mississauga, you can check out this Insauga piece. I definitely have added the ones listed there on my to-eat list.