I'm late to the party, but McEliece codes have also been around for a very long time, predating AES by a fair margin. The biggest problem with them is that the public keys are gigantic and the private keys are very large - even bigger than the keys used in lattice-based cryptosystems. This has caused them to always be a sort of fringe form of cryptography.

The good part is that McEliece codes are based on a proven NP-hard algorithm, so cracking them in polynomial time needs P = NP.