EXT has just attracted Flybe as a sort of low cost operator and is I believe smaller than HUY at present in passenger number terms.
I would not have thought that EXT's catchment area was any better than HUY.
Flybe have stated they intend to open another base in due course. Unless they go somewhere that already has a low cost airline base, as far as I can see the only two English options are HUY and NWI. I am ignoring BOH because Flybe have a big operation next door at SOU and would be unlikely to compete against themselves. Wouldn't they?!
Hull is a pretty big city in its own right.