The UHF connection is by far the most popular type used in Amateur Radio. The UHF male (plug) is known as "PL-259" and the female (jack) is known as "SO-239." Typically used in applications to ~400MHz.
The QC for Bird connection is popular in many types of testing equipment. Used in load resistors, attenuators, absorption wattmeters, wattmeters of many different makes, and most line sections. QC for Bird adapters are easily field changeable by removing and replacing four screws.