this is a rather difficult problem. As SirDice says, algorithm strength is not proportional to strength. Clearly, the more bits you use to encrypt the more possibilities you generate for a brute force algorithm. However, if the encryption algorithm is slightly flawed in that (making up an example) it always encrypts "e" to "47" and "m" to "~!" the odds drastically change.

Thats before you even consider the data being encrypted or the user. A user that sets an encryption key to "password" with the best algorithm in the world still has a problem. Also, when you encrypt things like source code you create a frequency analysis vulnerability as source code contains many repeats of words like "void", "while", "if", "else",.....

Short answer, "strongest" encryption is hard to define.