This all depends on where you live. For example: In the USA, it is Angus that is the most common beef breed found. For dairy, it is the Holstein. In Canada, the most common breed is Simmental, closely followed by Red Angus, Hereford, and Angus. Worldwide, the most common breed is actually Brahman, though it isn't as popular in the U.S.
As a side note, depending on how you run the numbers, the most "popular" breed of beef cattle is actually also Holstein. This is because the majority of beef consumed is through the fast food industry for which a large portion of the beef is rendered dairy cattle.
All cows can be used for beef, there really is no common type of cow. Dairy and beef cows are just as common as the other in being used for beef. However, steers (castrated males) and heifers are more common because they have no breeding/reproductive purpose in a herd, and are thus simply grown and fed for beef.
From what I know, Brahman and Brahman-crosses like Brangus are more commonly found in Texas than any other breed including Texas Longhorns.
Holstein
Angus cattle are the most common of the beef breeds and Holstein cattle are the most common of the diary breeds.
Most of the cattle in NZ are Dairy cows, and Frisian is the most popular breed because of its good production quantity. (As measured by Milk Solids.) Jersey cows used to be the common dairy cows, but no longer. For Beef cattle, Angus would be among the most popular. Hereford are another popular beef breed.
Jersey
Milking Shorthorn's.
It would have to be the Holstein.
Angus cattle are the most common.
A Holstein is a breed of large dairy cattle known for their distinctive black-and-white coloration. They are one of the most common dairy cattle breeds worldwide and are valued for their high milk production. Holsteins are easily recognizable by their black and white patches or sometimes red and white patches.
Dairy cattle.
Angus.
Holstein-Friesian cattle, often referred to as Holsteins, are a breed of dairy cattle known for their high milk production. They are black and white in color and are popular in many countries for their efficiency in converting feed into milk. Holsteins are one of the most common dairy breeds worldwide.
This breed is a dairy cattle. The standard colour is black with white markings. They are popular for their large amount of milk production. The fat percentage is about 3.5%. The Holstein-Friesian is the most popular dairy cow in Australia.