Marvel Post-Credit Scenes - Ranked From Worst To Best
13. Captain America: The Winter Soldier (No. 2)
After Aldrich Killian and Malekith, who had a pre-existing relation to the hero forced into the plot out of nowhere, the Winter Soldier was refreshing; the relation was plotted out four films ago. You can question whether it was worth attempting to keep the assassin's identity as Steve Rogers's childhood friend Bucky Barnes a secret, but it helped strengthen the character who, along with Loki, looks set to be a recurring anti-hero throughout the MCU.
That he wasn't a straight-up villain should have been obvious, given that Barnes saves Cap at the end. Just to hammer the point home though, he begins to discover his past in The Winter Soldier's second post-credit scene.
Milling around the Captain America exhibition at the Smithsonian, the sequence gives a nice moment of realisation for Bucky that pointed in the direction the standalone C.A. movies will take. As with Thor: The Dark Worlds second scene, this is a plot point that really belongs in the main narrative, but as it's not as integral to the main plot (which was really about the fall of S.H.I.E.L.D.) and more setting up a key element of Captain America: Civil War, it's easier to let it slide.