Ask whether a loose action figure or one sealed on its original card is "worth more," and you will get a confusing answer, because you have asked the wrong question. Carded examples generally command more money, yes — but leading with value misses the decision that actually matters and that should come first: what kind of collector are you? The honest answer to that determines everything, including whether the price premium is even relevant to you.
The two collectors
There is the preserver, for whom the object's untouched, sealed, original state is the entire point — the figure as a time capsule, never to be opened, value tied to that pristine, frozen condition. And there is the player-at-heart, for whom the figure is meant to be held, posed, displayed in the open, enjoyed as the toy it was made to be. Carded collecting is the first temperament; loose collecting is the second. Neither is correct. They are different relationships with the same object.
The trap of trying to do both
Some try to have it all — a sealed one to preserve and a loose one to enjoy. That is a legitimate choice with deep pockets, but for most people it is a recipe for spending double and committing fully to neither. Pick the relationship you actually want with these objects. If you will never open it, collect carded and accept the premium. If you want to pose it on a shelf, collect loose and stop mourning the card you were never going to keep sealed anyway.
The point
Value follows from condition, but your happiness follows from buying in line with who you are. Work out whether you are a preserver or a player first. The "which is worth more" question answers itself once you know which collector you actually are — and you stop paying for a version of the hobby you were never going to live.