Patching is a good option too, preceded by a flush, and followed by a pressure test. What I see often is debris piling up in the bottom of the heater box and rainwater then wicking up to the core. They have been easy fixes for me.
But, I suppose at the cost of labor these days, if you have to pay someone to patch it, it might be cheaper or smarter to replace it. And if I had a choice, I would leave the aluminum ones alone.
