By "too big" are you referring to the size of the plant itself, or the fruit? For a beginner, I would suggest a determinate variety rather than an indeterminate, as the later continue to grow much taller and need far more support. Even with a determinate, a large beefsteak variety will need significant support. As to the fruit amount, a grower can always thin the production by removing some of the small fruits early on. With flavor, remember tomatoes are very heavy feeders throughout their entire growing cycle. A missing nutrient (or micronutrient) may prevent the fruit from producing all the sugar of which it is capable. Additionally, tomatoes historically have been an "acidy, aka sour" fruit. Prior to GMO, heirloom growers tended to save seeds from, and selectively pollinate the plants which worked best for them. With open pollinated seeds the acidity can be more hit and miss,