Go for AES.
AES is the successor of DES as standard symmetric encryption algorithm for US federal organizations. AES uses keys of 128, 192 or 256 bits, although, 128 bit keys provide sufficient strength today. It uses 128 bit blocks, and is efficient in both software and hardware implementations. It was selected through an open competition involving hundreds of cryptographers during several years.
DES is the previous "data encryption standard" from the seventies. Its key size is too short for proper security. The 56 effective bits can be brute-forced, and that has been done more than ten years ago. DES uses 64 bit blocks, which poses some potential issues when encrypting several gigabytes of data with the same key.
3DES is a way to reuse DES implementations, by chaining three instances of DES with different keys. 3DES is believed to still be secure because it requires 2112 operations which is not achievable with foreseeable technology. 3DES is very slow especially in software implementations because DES was designed for performance in hardware.
http://www.icommcorp.com/downloads/Comparison%20AES%20vs%203DES.pdf (offline, still in the Web Archive)