Size   Size does not have a great bearing  in telling if the quality of a tomato is good or not.  Size is more a matter of preference and of tomato variety.  Good quality fresh tomatoes are those that are not over-ripe, but are form, well formed, plump, smooth, of good color, free from serious blemishes, and that have a good well balanced flavor.  That means not sour or overly sweet.  Deformities and scars around the blossom end cause waste but does not damage the flavor quality of the tomato.  Puffy or watery fruit is poor flavor and have low yield.  The best-flavored tomatoes are allowed to ripen on the vine.  Tomatoes  that have been damaged by chilling are never of good quality, but chill injury is difficult to recognize