So there are several types of transistors:
Combine all that with the various flavors of each (NPN, PNP, enhancement mode, depletion mode, HEXFET, etc) and you've got a wide array of parts, many of which are capable of accomplishing the same job. Which type is best suited for which application? Transistors are used as amplifiers, digital logic switches, variable resistors, power supply switches, path isolation, and the list goes on. How do I know which type is best suited for which application? I'm sure there are cases where one is more ideally suited than another. I admit that there is some amount of subjectivity/overlap here, but I'm certain that there is a general consensus about which category of applications each of the transistor types listed (and those I left off) is best suited for? For example, BJTs are often used for analog transistor amplifiers and MOSFETs are generally used for digital switching.
PS – If this needs to be a Wiki, that's fine if someone would like to convert it for me