Which method of password cracking takes the most time and effort?

Brute-force cracking, in which a computer tries every possible key or password until it succeeds, is typically very time consuming. More common methods of password cracking, such as dictionary attacks, pattern checking, word list substitution, etc. attempt to reduce the number of trials required and will usually be attempted before brute force.

References: https://en.wikipedia.org/wiki/Password_cracking