I like to experiment with different brands of crushed tomatoes. 6-in-1 is topnotch (when they're fresh). Contadina is good, as is S&W in the west (last time I had them, they were excellent). I'm still undecided about Progresso and Muir Glen. I find that my local grocery store brand (Jewel, owned by Albertson's) is very good. I always add sugar to my sauce.
You can also buy whole peeled tomatoes (genuine San Marzanos from Italy are excellent), drain them, and crush them by hand.
My sauce (uncooked) formula is:
1 28-oz. can crushed tomatoes
1-2 cloves garlic, minced or crushed
@1 tsp. Kosher salt
@1 tsp. sugar
@.50 tsp. Italian seasonings--I prefer a "Pizza Seasonings" blend I buy at Cost Plus
A few shakes of red pepper flakes
Obviously the seasonings you add can be adjusted to your taste.