Once you go past a decent amount of frames, the cost of the subfleet doesn't matter.
There must be a reason why airlines are not ordering the 319neo, all the airlines are upguaging to the 320 and 321 - obviously the economics don't work.
EZY is in an interesting position, and if they order the rumoured amount of the Cseries, could put them back in the game with Ryanair, as their airbus order was on the light side.