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Managing the municipal solid waste (MSW) is a task that requires the combination of multiple strategies in order to follow the concept of circular economy. Waste-to-Energy (WtE) plants are producing electricity and heat but also have other byproducts that need to be disposed or can be reused. The standard method for assessing the WtE plants is the utilization of the R1 formula. The R1 formula has several limitations and is not able to integrate more parameters like the recovery of metals. The integration of the climate correction factor can improve the R1 up to 1.25 times but this factor is related to the Heating Degree Days, which is a rapidly declining value due to climate change. Contrary to the R1 Formula, the 3T Method is a novel method that can take into consideration all the range of products like syngas and biooil in a thermodynamically consistent way. These two methods were used to analyze three characteristic incineration plants and two gasification plants and this is the first time that this comparison is being presented. The results showed that the two methods have different ranges of returned values, with the R1 returning values (usually) between 0.5 and 1.1 and the 3T method returning values between 0.2 and 0.3. The 3T method on the one hand promotes high electrical efficiencies, i.e. 3T values approach the 0.3 mark for 30% electrical efficiency, and on the other hand promotes polygeneration where the recovery of char and metals can elevate the 3T value well above the 0.3 level for only 15% electrical efficiency and 70% metal recovery.