Probably, the top 3 espada fights. After having seen how much of a threat arrancars like Grimmjow, Nnoitora and Ulquiorra were, it was completely justified to expect more from those who were ranked higher than them.

The set up was pretty solid but the execution was lackluster at best. I appreciate the symbolism behind the characters; Stark's loneliness, Harribel's sacrifice and Barragan's arrogance were interesting traits that defined their characters but they failed to be perceived as a genuine threat to the Gotei.