What about Bucuresti?
A lot depends on the airline group. Warsaw gets people who fly in on Qatar Airlines and Turkish too.
As a hub, it's obviously smaller than the big ones like Frankfurt and Schiphol (ugh) but much nicer and less stressful than some of its rivals like Vienna, or Dusseldorf. Copenhagen is sort of a 'mini-hub' now and there are plenty of routes that are via either Warsaw or Copenhagen. Munich seems to be growing as a hub now and isn't at all bad.
the war presumably has gotten in the way of that
I've changed planes at the new one in Istanbul (horrible, as nasty and as totalitarian-looking as the new Berlin airport and even more expensive in the shops/bars) a few times over the past few months and each time, I noticed that around half the flight are from r*SSian provincial airports. They are really cashing in on the war.