[logfromblammo]

Preferably tomatoes grown in volcanic soil, like San Marzanos.

It is well worth buying one can of several different brands of tomato sold in your locale, and making experimental taste-test batches with all other variables held constant. With good quality inputs, you can beat the pre-made jarred marinaras every single time, using nothing more than a very basic recipe and a minimum of cooking skill.

Exercise caution. Once you know how to make a good sauce, you will never be able to stand eating at Olive Garden again.