Hi Otis,
Fresh tomatoes are great on pizza, however, they do require special treatment and if you intend on using them out of season, they can become very costly and difficult to handle–with not the greatest results.
The best tomatoes for all around pizza topping are Roma tomatoes, otherwise known in some parts as egg tomatoes, plum tomatoes or Italian tomatoes. They are slightly pear shaped, have thicker skins and thicker flesh with less seeds and they are best for cooking because they have low moisture and great flavor. The best way to prepare them for pizza is to seed them first and then slice into strips or cut into slices or large dice.
To seed them, cut them through their circumference and simply squeeze the seeds and excess juice out. You can also cut them lengthwise and hollow out the seeds using 2 fingers on each half.
Romas can be used year round, but they become really pricey in the winter and you have to purchase a number of cases at a time to allow them to ripen for a few days before use.
As for other fresh tomatoes like heirlooms, sweet 100’s, cherry tomatoes and beefsteak tomatoes, they are best used in season as a specialty topping. I don’t seed these when I use them, but then again, I tend to pair them with just a few toppings so their juices don’t make things soggy. (Put the cheese down first and the tomatoes on top, that helps the moisture factor).Summer is the best time to do lots of variations on the Margherita pizza using a mix of tomatoes in all sizes and colors.
If you want year-round fresh taste and consistency, use crushed fresh-pak tomatoes and they will give a brighter, fresher, flavor to your sauce. If you make your own fresh tomato sauce, I would stick to doing it as a seasonal special.