In S E England I think it is coming down to which airport is nearer/ easier. Cost of getting to airport . time to get there and parking are more important than the fare.
Even then BA are at a disadvantage as LHR is the most expensive, perhaps Mr Cruz can get his countrymen to cut the charges at LHR to help his cruzade.
I have just booked a trip to France at end of month and as both BA and EZ go from LGW my preference and proximity to LHR means the slight advantage in better times means I will choose EZ over BA .
If they go this way on LH then BA are toast