I grow heirloom tomatoes in the United States, and they are spectacular. The tomatoes available in the grocery store pale in comparison to anything grown in your own garden.
This probably has more to do with the fact that supermarket tomatoes are picked before they fully ripen on the vine (often green). I also enjoy growing my own (Brandywine is a favorite), and letting it ripen on-vine to the point where it's probably hours away from falling off or starting to rot results in a much better tasting tomato than jumping the gun.