Which Theme? Please Help Me Choose!

Hi there!

I'm currently having what a lot of people would think is the opposite of a problem. I can't pick a theme for my game.

Here's what the game is like, in roundabout terms...

-Short, 10-15 filler card game, co-operative set collection (that's the important bit, join me at the "###" if you don't want/need to know more)
-40 card deck, 5 suits; 4 useful, 1 not useful
-Set collection game, collect 2 of the 4 useful suits and avoid the one not useful suit
-4 turns per round, 1 action per turn, max hand size of 3
-Rounds end after the forth turn
-A second part of the game happens after each four-turn round, which gives a second chance to players who couldn't collect their suits
-A new round begins with all cards in the discard pile remaining there
-The game ends when the deck is gone

I know that's not a very good way to describe it, and gives you no handle on what's going on, but I figure it's better than nothing.

So the issue I'm having is that I can't figure out what theme I want to use for this game. I've essentially found a handful that fit nicely, but I would like an outside opinion on each.

### I'll list the theme, why I like it, and why I DON'T like it. Please tell me which of these themes YOU like the most for a 10-15 minute cooperative filler card game with set collection... (pros/cons also skippable to another "###" at the end of the post)

1) Zombies (Heavy Theme)

Pros
-The set collection aspect lends itself to survival items, which gives players the "we need to survive" motivation while playing
-The 4 suits are Food, Water, Weapons, and Medicine; easy to rationalize

Cons
-Zombies are played out, and the game does nothing to stand out in a saturated market
-The artwork would look bland and like every other game
-Age restricting
-Zombies

2) Castaways Sailing Home (Heavy Theme)

Pros
-Deep DEEP role-playing and lore that I developed for the game. Complete with player cards that had family, friends, and enemies which altered how truly co-op the co-op was each game
-The set collection aspect lends itself to survival items, which gives players the "we need to survive" motivation while playing
-Could have really hella cool artwork

Cons
-Nobody will want to get deep into role-playing in a filler game
-The re-playability stands artificially on the back of the role-playing (as compared to the other types. It's still the same game, but the alliance system wears a little thin. It feels like it replays FOR the role-playing, not WITH it)
-The set collecting items are the same as the zombie theme, except the weapons are replaced by clothing. And clothing never sat right with me as an essential to collect when stranded
-Age restricting

3) Stranded Astronauts (Heavy / Medium Theme)

Pros
-Sci-fi theme of astronauts skipping from abandoned colony to abandoned colony, picking up the supplies to make it back to the only colony left standing
-The set collection aspect lends itself to survival items, which gives players the "we need to survive" motivation while playing
-Neat "Dead Space-esque" aesthetic
-Possible role play

Cons
-Literally everything from the castaway one
-Because it's the castaway one
-In space

4) Flower Growing (Light Theme)

Pros
-Open to most ages
-Cool artwork potential
-Set collecting seems natural as choosing flowers to grow
-Very filler-ish style to it, unoffensive and light

Cons
-There's nothing to be earned by running the deck out; lacks an end goal
-It's not very co-operative, or even semi-cooperative; lends itself to competition
-Kind of bland. I could definitely see people going "ah yes, a game where I grow flowers with my friends. That sounds about as exciting as actually doing that."
-Not much in terms of conflict to keep you going

5) Monks in Training (Light / Abstract Theme)

Pros
-Open to most ages
-Cool artwork potential
-The collection of sets would be things like "Truth" and "Honor"; feelings as sets rather than items
-End goal after finishing the deck is Enlightenment, which is hella satisfying as a concept, and keeps you playing
-Light, unoffensive theme that is only present if you want it to be (and I would make sure it was actually unoffensive as well. I'll do research to make sure I'm not putting ignorant bullshit into the world)

Cons
-The second part of the game makes little to no sense in this version (I can explain that in another post if anyone wants to know about it. I haven't nailed down exactly how it works yet, so that's why I'm not saying much about it)
-The maximum hand size in this feels completely arbitrary, wherein all other versions, it has a thematic reason
-If the theme ends up being offensive to some people, I'm kinda stranded

### So there ya go. The themes are...

Zombies
Castaways
Space Castaways
Flowers
Monks

...in case this was too long and you didn't read. Which would you like more in a 10-15 minute co-op card game with set collection?

Thanks for reading!! And sorry for the disaster of a formatting job. The lack of bold, italics, and line breaks is awful.