What sort of pizza are you making? There is no sauce that is best for every style.
I prefer to pass them through a food mill. You can crush by hand or blend. If you blend, just a few quick pulses. It would be better to under-blend than over.
For Neapolitan, never add anything except a bit of salt - and maybe a TINY bit of sugar if they are a little bitter, but that would be unusual. I always use whole peeled tomatoes that have a basil leaf in the can. My favorite is the Cento Italian Tomatoes that come in the 35oz can.
For NY and other styles, i might also add a bit of oregano, and maybe some EVOO, but that's it. Pizza is about balance. If your sauce is a flavor bomb, you've already lost. Don't forget that you can always add some herbs and/or spices on top of the sauce when preparing the pizza. If you make several different pies with different toppings, you will likely find that different herbs/spices go better with different pies. If you put them in the sauce, you get them on every pie whether they go well there or not.
With respect to San Marzano tomatoes, San Marzano is a variety of tomato. A D.O.P. San Marzano is one that was grown in a particular region of Italy and that meets certain specifications. D.O.P. is not a quality guarantee. In many cases, you can find better tomatoes for far less money.