Look for firm heavy fruit with no soft spots. Newer grapefruit will be shinier on the surface and is perfect for out of hand eating. However, dull, mildly dehydrated skin and slightly softer grapefruit is best for juicing.

Varieties Courtesy of Florida Department of Citrus:

Flame Grapefruit
Flavorful, sweet and juicy. Flesh is red in color and usually seedless.

Ruby Red Grapefruit
Medium to large size, usually flattened at each end. Smooth yellow peel with areas of pink to red blush. Segments have characteristic pink to reddish tinge. Few seeds.

White Seedless Grapefruit
Medium to large size, usually flattened at both ends. Peel is yellow, smooth and thin. White to amber colored flesh and almost seedless. Easy to section. Excellent flavor and plenty of juice.

More about Florida Grapefruit