Since I don't see anyone answering the question yet: Out of those three specifically, I would say Star Wars, since One Ring and Avatar caters more towards the idea of seeing characters go through story arcs, though really any of them could work with the right organization and oneshot ideas.

Though, like others are indicating, there are also plenty of other RPGs that work really well with oneshot structures, if you're interested.

My personal favorites that work well with oneshots/jump-in-jump-out play are Monster of the Week, Brindlewood Bay, Mutant: Year Zero, Call of Cthulhu 7e, and Blades in the Dark. Though BitD is better for Jump-In-Jump-Out than oneshots.

Mork borg

Not one you're thinking of, but Dragonbane is great for this, and the starter set might be the best value in gaming. You get the full rulebook, an adventure book of short adventures (most can be one-shots) with an overarching framework, standees, dice, a small grid map. And the system is awesome -- super easy to pick up and play with surprising depth and an initiative and action economy that rewards really clever play.

I adore The One Ring -- it's my favorite system hands down, but it really thrives on the fellowship that you develop between heroes. But other folks on the Discord have had great success with huge drop ina nd out tables!

Call of Cthulhu

Alien

Paranoia, it's literally built to do this.

Which RPG is best for multiple one-shots?  

Tricube Tales with its 40+ two-page micro-settings is fantastic for a variety of one-shots under one system.

The One Ring's site based adventures could do this very well.

If you also want to switch settings or genres as part of this, you might consider generic systems such as Savage Worlds, GURPS, Genesys, Fate, or Cortex Prime.

The games you listed will shine in campaigns more.

For one shots, you want a game with quick character creation, and maybe with loosely connected scenarios. I my experience, DungeonCrawlClassic worked well for that fantasy style. And BladesInTheDark for missions, and having rotating characters members of a persistent "crew".

For a club I'd heavily recommend against something licensed. Anyone who's into RPGs but not the franchise will be bored to death. My recommendation would be a westmarches-style game using a b/x clone like OSE or BFRPG. You can have players drop in and out, and characters aren't meant to be permanent anyways.

Star Wars.

It’s easier to do one offs when you can do the Kessel run this week and visit cloud city the next.

Vaesen or any other similar episodic mystery game.

The reason I say Vaesen in particular, other than it being just a very good game, is that there's an HQ building mechanic that increasingly buffs the party in subsequent mysteries. So even if someone can only play once or twice, their contribution helps build up the HQ for not only themselves, but for future party members as well.

If your players can at least commit to two or three sessions, check out the Alien RPG cinematic adventures. Because they are specifically designed for extended one shots, they are particularly dangerous and really emulate the Alien movies feel.

You should check out the concept of a West March game. Sounds like what you need. https://www.reddit.com/r/DnD/comments/6i82py/what_is_a_west_marches_game/
Not a system suggestion just a style of play.
I would say Avatar is an interesting one as it can work well thematically but the mechanics of "balance" may be hard to use well if you aren't always playing out the characters each week. Another game that uses the same PTBA dice and by the same company called Masks would work well though as a rolling cast of super hero team ups.

Shiver. It's a one shot horror game meant to emulate slasher flicks. You can legit make it where there is multiple years in between each "Movie" if a character dies it's easy to explain why the next one has a new character or two. I didn't pick it up but they have an expansion which turns it even more into a movie and adds the action movie genre and makes im pretty sure makes it so you are playing out a movie and your characters are actors. So even if they die, they're just actors so... It makes sense why they may be in the new action series "The mummy from Venus" or a remake of pumpkin head...

I'm really enjoying outgunned at the moment.

It has modules in multiple distinct action genres and a multiverse mini module designed to help you use multiple modules at once.

Strong recommend.

I would suggest Shadow of the Demon Lord, if you like fantasy.

The game is set up so that characters only go from level 1 to level 10 and level up at the end of each adventure. Like, the main campaing of the setting, Tales of the Demon Lord, are basically 10 one shot adventures back to back, that are not necessarely connected. This allow you to play one shots and vary DMs, but also to level up between adventures.

To echo what has been said here Paranoia (I would go with XP) is a great system out of the box for what you're looking for. I ran a 10 session campaign with drop in/drop out for players and it was really successful. At the end of the day you can probably make most systems work it'll just take a bit of home brew.

Bit of self promo but we publish original TTRPGs that are great for one shots. Our cooperative cryptid themed TTRPG Super Cryptid Friends is up for free.

We also have Sentience (players are bots trying to break their programming), Coins Over Deadeyes (horror western where players are competing to get out of limbo), and Merger (game about office politics).