At this current point in time according to Steve Rogers. Otherwise I like to imagine they’re all equal. (and in the comics I’m willing to concede that Bucky’s worth at least 2 Tony’ according to Steve)
Yeah, I know that Tony gains more worth as Steve gets to know him, but BUCKY IS ALWAYS MORE IMPORTANT.
KID SIDEKICK AND/OR FELLOW ORPHAN BEST FRIEND (depending on the universe) BONDS RUN DEEP.