I don’t think there is a simple answer to your question, but I strongly suspect that factors other than ETOPS will drive the economics of the aircraft. Economics will be influenced by existing fleets, route structure, traffic densities, number of aircraft needed per day to meet the demand at a reasonable load factor, range requirements (and, yes, the need for ETOPS capability).
I know that Direct Operating Costs are important (they include fuel, maintenance [line, airframe, engine overhaul reserves, components and LRU inventory charges], total crew and attendant employment costs, navigation and landing fees, passenger catering and aircraft lease charges). But the total annual costs of operation, and consequently trip costs, are also influenced by aircraft utilisation and number of available seat-miles (ASMs) generated.
In simple economic terms, the two-engined aircraft is often preferred to the four engined aircraft where ETOPS allows. But then the real world can intervene on a particular route - one of the medium range analyses I have shows that the 777-300 and A340-600 have virtually equal trip costs on the route, but the 777-300 has a 32-seat higher standard seat capacity. The 777-300 was therefore able to operate at one [daily] frequency lower than the A340-600 while traffic grew, and so generated a total higher margin.
777 vs a 747? I reckon the 777 wins often, until the route gets busy and you need two 777s to compete with the 747. The costs of ETOPS checks don’t really feature in the sums.