I know that Rijndael and AES are pretty similar and AES is just a subset of Rijndael, and I have read that Rijndael can have 256 bit blocks while AES has "only" 128 bit blocks.
The problem is that I have no real idea of cryptography my question is what is more secure? Is "standard AES" more secure or some of the tweaked options using Rijndael? Right now I am using
MCRYPT_RIJNDAEL_256 in PHP which is (as far as I can tell) Rijndael with 256 bit block and key size while AES-256 has 256bit key but "just" 128 bit blocks.
The point is in the end whether to use AES or Rijndael?
Also what mode would be best for security/performance? Right now I have ECB since that was used in a tutorial at that time.
Is there another algorithm that is even more secure? It should be fast, since I am doing a lot of crypto stuff using it, but still stay secure.