I usually don't freeze the finished sauce, as I make just enough for the pizza I'm making. If there is any leftover, I will freeze it and add more to it later on. I don't notice a difference in flavor.
I do freeze the tomato by itself. I use a jar, or whatever container I have available.I thaw in the fridge, take out what I need, and refreeze the rest. When I'm out, I open a new can. It works for me.
I started doing that because the variation in flavor between cans. If I didn't like the finished sauce, I was stuck with a whole container. Now I just make small batches based on what the tomatoes taste like at the time, and don't wreck whole cans.