Depends on what you mean by "cost effective", and what expectations you have of cooking evenness.
A solid fuel stove will probably be cheapest (grandma style wood or coal oven), followed by a resistive electric stove and the most expensive stove being induction electric. This covers the initial cost of the stove itself. The quality of heating goes along the same direction: uneven heating with coal/wood, even but sluggishly responsive heating with resistive, great heating with induction.
But over the lifetime of your stove, the most costs are probably caused by the fuel costs. Induction as technology has much higher efficiency than resistive heating, so you will save much from your electricity bill if you use induction instead of resistive. How long will it need until the break even point in initial investment vs electricity savings depends on the exact models of stove you are comparing plus your cooking habits/frequency.
As for wood or coal, they can be cheaper or more expensive than electricity for you depending on where you live. But most people would not use them for cooking even when they are much cheaper, due to the added hassle. I only mentioned them here because you insist that your primary criteria is "cost effective".