Lucknow has Shatabdi,AC SF and Gomti which run full,Kanpur has CNB Shat which again runs with somewhat good patronage,BSB has a lot of other trains which people prefer over SG at times,Taj is not in league (Sorry)
ALD has AD and UCR exp but AD isn't regular and Nobody goes by UCR exp So Prayagraj is my pick,You should have added Gorakhdham from Gorakhpur ,It'd top this poll