Simple substitution and transposition ciphers are vulnerable to attacks that perform frequency analysis. In every language, there are words and patterns that are used more than others.
Some patterns common to a language can actually help attackers figure out the transformation between plaintext and ciphertext, which enables them to figure out the key that was used to perform the transformation. Polyalphabetic ciphers use different alphabets to defeat frequency analysis.
The ceasar cipher is a very simple substitution cipher that can be easily defeated and it does show repeating letters.
Out of list presented, it is the Polyalphabetic cipher that would provide the best protection against simple frequency analysis attacks. Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, Chapter 8: Cryptography (page 507). And : DUPUIS, Clement, CISSP Open Study Guide on domain 5, cryptography, April 1999.