In general the choice of one encryption method over another has more to do with bid requirements or compatibility than it does with the merits of the method.
The encryption methods supplied are:
Blowfish - developed by Bruce Schneier as a replacement for
Twofish - an earlier method developed by Bruce Schneier DES - one of the AES competition finalists
AES - Advanced Encryption Standard - the latest government standard - chosen via an open submission/discussion/analysis process
Rijndael - the same as AES (rijndael is the method chosen for AES)
DES - Data Encryption Standard - the previous government standard 3DES - DES with a key size three times as large
Safer+ - another AES submission developed by Cylink Corporation
RC2 - developed by Ron Rivest for RSA Security
Additional References:
Blowfish - http://www.schneier.com/blowfish.html
Twofish - http://www.schneier.com/twofish.html
Safer+ - http://csrc.nist.gov/CryptoToolkit/aes/round1/conf1/saferpls-slides.pdf
AES/Rijndael - http://csrc.nist.gov/CryptoToolkit/aes/rijndael/
DES - http://www.itl.nist.gov/fipspubs/fip46-2.htm
3DES - http://csrc.nist.gov/cryptval/des/tripledesval.html
RC2 - http://www.rsasecurity.com/rsalabs/node.asp?id=2249