Winch one is it for you?
I would go with Weidman fight.
Excellent wrestler,former champion(just in his previous fight already),awesome resume etc.
And everything Weidman did and tried failed to work on Romero,even when he went with his best skill winch is wrestling he got schooled.And all of a sudden Romero was like alright let's give people what they want and KO's him brutally with a flying knee.
Look at this wrestling clinic by Romero
Rockhold fight was maybe just as impressive,striking only and again nothing worked on Romero,showed awesome defence and went on to KO another former champ
Some other impressive wins:
Tavares-showed beauty of his wrestling,pure domination
Kennedy-wasn't touched until Tim had to cheat and got brutalized for it in the next few minutes.
Machida-Did better standing vs a striking master and KO'd him brutally on the ground after first and only takedown.