To me the one that comes to mind was Wanderlei vs Ricardo Arona. This was an epic matchup at the time, Wanderlei was in his prime and absolutely dominating his weight class. Arona was a beast with wins over Hendo, Ninja Rua, Mezger, Jeremy Horn, Sakuraba, and most people thought he beat Fedor Emelianenko and was robbed in the decision. He would also go on to crush Alistair Overeem in the first round, the man was a serious force in that division.
I remember when they first met I was as pumped as one can be about a fight. Arona would go on to end Wanderleis streak of dominance at 205, and Wand would avenge the loss with a decision win of his own, but both of their fights kinda disappointed in the sense that there was not much epic or memorable moments. They each won a decision, and the only thing I can remember about either of those fights is Aronas leg kick that knocked Wand down.
Any other fights that looked killer on paper but the fight itself was pretty forgettable?