Fresh or Frozen
Fresh turkeys are turkeys that are quick-chilled to 40°F (4°C) or lower and have been stored at a temperature greater than 26°F (-3°C). This means, it is possible that the turkey could be partially frozen (if stored for a while). They should kept in the refrigerator after purchase and cooked within two days.
Both fresh and frozen turkeys produce excellent results when roasted properly. In general, fresh turkeys cost more than frozen, so I use frozen turkeys.
Basted or Unbasted
Basted turkeys have been injected with a sodium-based solution to increase the juiciness of the bird. Flavor enhancers, fat, broth, or stock can also be injected into the turkey. In the United State, it is required by law that labels must include a statement identifying the total quantity and common name of all ingredients in the solution. The United States Department of Agriculture (USDA) website provides this example: "Injected with approximately 3% of a solution of _____________ (list of ingredients)."
In general, basted turkeys are more juicy (when roasted directly), but have an off taste. For the best turkey, buy an unbasted one and brine it for a few hours before cooking. Don't brine a basted turkey since they already have a heightened salt content.
Fryer/roaster turkeys are young turkeys usually less than four months old. These are generally between 4 and 8 pounds (1.8 and 3.6 kg) and are very tender.
Young turkeys are between 4 and 7 months of age. They are sometimes referred to as young roaster turkeys and are also very tender. I recommend using either fryer/roaster or young turkeys for roasting.
Yearling turkeys are around 12 months old. The skin and meat are moderately tender and can still be roasted well.
Mature turkeys are over fifteen months old and should not be used for roasting since they will produce fairly tough meat.
To figure out how much turkey you need to roast, use the 3/4 pound (1/3 kg) per person rule of thumb. A ten pound turkey can be expected to feed 12 to 14 guests.
Free range or free roaming turkeys must be allowed access to the outside while being raised. This does not affect the taste of the turkey.
Hen turkeys are female turkeys and generally are 15 pounds (7 kg) or less. Tom turkeys are male and are typically more than fifteen pounds. The sex of the turkey has no bearing on flavor, texture, or tenderness.
Kosher turkeys are turkeys that have been prepared under Rabbinical supervision. Often, they are sold with a layer of salt coating the turkey increasing juiciness and saltiness. These turkeys do not need to be brined, but soaking them in water may increase their tenderness by increasing water content prior to cooking.
Minimally processed turkeys are supposedly minimally processed. However, processing can include traditional processes for preparing meat such as smoking, roasting, freezing, drying, and fermenting. Generally, this isn't an issue when buying a turkey for roasting because they all be minimally processed.
Although there does not yet exist a man-made turkey, there are Natural turkeys. Natural turkeys do not contain artificial flavors, food coloring, chemical preservatives, or any other artificial ingredient. In the U.S., the label must explain the use of the term "natural" (for example, no added colorings or artificial ingredients; minimally processed). Natural turkeys generally have the best flavors without the chance of the turkey tasting artificial. They also cost more.
The label "no antibiotics" can be used when the turkey producer proves to inspectors that the turkeys were raised without antibiotics.
Although the U.S. government prohibits the use of hormones when raising turkeys, the label "no hormones" can still be found on some turkeys. According to the USDA, the claim "no hormones added" cannot be used on the labels of poultry unless it is followed by a statement that says, "Federal regulations prohibit the use of hormones."