The RPG Experience

I've referred to this in a previous post about RPGs as that style of play choice which exists between a campaign and the "one and done" scenario.

What makes that choice for you and what are the reasons to choose one over another?

Campaign Play

This exists in a number of formats but the core of campaign play is the setting and that there is a plot far wider than that played out in the gaming sessions themselves.
Campaigns involve many sessions of linked-play similar in many respects to the chapters in a book, the episodes in a TV show or the issues of a comic book.
A key reason to opt for campaign play is not simply to develop the story but also to develop those characters who contribute to the story.

One And Done

As I've said previously I've used the one-shot scenario to demonstrate a RPG but also at conventions to explore a particular element of storytelling or indeed showcase a specific mechanic in a game.
The Polar Light scenario referred to in Character Motivations was built on a fairly simple premise but was written to explore how the characters would react as the plot developed.  As I've said before the scenario has been different each time I've ran it.
The Star Wars EotE scenario I ran for Free RPG Day is designed to cover as many bases as possible mechanically.  It also explores how characters react to the situation but that's more of a bi-product of the situation (a post for another time perhaps) as the objective of that scenario is to use as many rules as possible so that the players experience the system fully.

Which one is the right one for you?

As ever that has to be a personal choice but I find both formats equally rewarding.
Few things in playing RPGs is more worthwhile than Campaign Play, particularly when the characters are really driving the story and where the GM has to adapt and change that story as a direct result of their actions.
Similarly playing one-shot scenarios or simply playing a few games of something else outside that Campaign can add to your overall RPG experience.  Plus those one-shots may develop into ideas for future campaigns...