I will copy paste my comment from the other thread:
Firebending is different that the other elements in the sense that the bender usually creates the element instead of manipulating like the others do.
Here is the volcano calc which resulted in 21 tons of TNT.And
here is another calc for the firebending during Sozin's comet which isn't an outlier anymore since we've found some feats closer to its value.
It should be noted though that powerscaling between different kind of benders should be avoided since each element functions differently.
Aiden also did a few calc
here , and
Bumi has a Building level feat himself .
So my suggestions are:
Elite firebenders - City Block level
Avatar Aang at his peak - City Block level
Korra - ? (not sure, it will depend on how the upgrades affect the characters she fough since it seems that she gets defeated/mached a lot)
Elite Waterbenders - Wall to Large Building level depending on the amount of water they have at their disposal
Earth benders - At least Building level (I'm pretty sure Toph has a couple of feats that can put her higher than that)
Airbenders - ? (Their feats are mostly around Wall level so we need to search for feats)
The physical durability of the characters is around Wall level but they have shields which will be upgraded accordingly.