How to repair my concrete slab porch.
Patching rarely works out, structurally or aesthetically. If you want the cost effective remedy then go with smashing it up and installing properly supported decking material. This will likely involve installation of footings for support joists.

A close look at the pictures reveals an underlying problem related to movement of the porch foundation, that is at least one of the root causes of the significant cracking visible in both the slab and the foundation. The proper fix would be to remedy the underlying problem. You wish the job to be "cost effective"; with the long term view, repair of the foundation would be the most cost effective because the problem would be solved and future repair costs would be minimized. It would, however, likely be the most expensive of your options.