Best small worlds

https://www.thesims3.com/assetDetail.html?assetId=4631460
Blue Bayou is a small louisana style world.Base game only, but
may use some store items, but if you don't own them it should
be okay, the game will just replace them.

https://www.thesims3.com/assetDetail.html?assetId=4718413
Fairview is a really nice world, but it may have some store items/CC items
can't remember.

https://www.thesims3.com/assetDetail.html?assetId=6719548
And Hope Springs.

I know quite a few small worlds, but most require store/expansion packs.

Try here - https://sims3customworlds.tumblr.com/

This tumblr has a menu tag for all kinds of worlds, small and tiny included.

https://sims3customworlds.tumblr.com/tagged/tiny-worlds
https://sims3customworlds.tumblr.com/tagged/small-worlds

You may be able to find something there that suits your fancy. Worlds should have requirements listed in the posts, they usually do. Just a note though, I don't think that tumblr has been updated to the present time, but it still may be useful for you, there are lots of little worlds listed there.

If you don´t mind building, because there are no buildings in this worlds, I would recommend:
Hylewood by Nilxis: http://nilxisdesigns.blogspot.com/2014/11/hylewood.html
There is a bigger version over at MTS: http://modthesims.info/d/625912/hylewood-edit-small-world.html
If you like a more South Sea´s feeling there is Isola by Rflong: http://myworlds-rflong7.blogspot.com/2013/01/isola-island-this-world-was-make-by.html
Both creators have a few smaller worlds, perhaps they have something else for you!
Then there is this side: http://www.mysimrealty.com/ They have a wide range of small/bigger/ huge worlds, perhaps you´ll find something for your liking
And this world by Volvenom is nice, too: http://modthesims.info/d/525625
You can look here, too: https://www.nraas.net/community/Worlds-Recommended-By-Wiki-Members the medium size worlds can be played by you too, perhaps.

The problem is that the small worlds mostly come without buildings. But if you want a world which has built lots then you need some more EPs. You can try to download some worlds with more EP content or with CC, but I would highly recommend to try this worlds out and play-test them in a different Sims 3 folder then your main game! (Which you should do with every world/CC by the way) Sometimes creators place bridges you maybe not own so the Sims can´t go to some places. Or use something from the store you don´t own. This can cause the game to crash.
Hopefully you get a world you like!

@StephSteb : in the description it is said that Positano needs all EPs and Sps, but the poster just has the base game. Sorry to be so nitpicking.

Go with AlexaKry's suggestion and look through the offerings by Riflong 7/13 or Nilxis. Those usually play well.

@GraceyManor The worlds you suggested are all large (2048x2048), and two out of three (Blue Bayou, Hope Springs) require several expansions.

"@StephSteb;c-17448600" wrote:
I just saw that, lol AlexaKry Had a duh moment!

Remmo has all the expansions. If it says it needs expansions then it does need expansions. If the world shows it only needs the Base Game but the description says it needs them, go with the description. :)

I just made a huge world using all the EPs and SPs and Store but the site claims you only need the base game. ;)

"Turjan;c-17448603" wrote:
Go with AlexaKry's suggestion and look through the offerings by Riflong 7/13 or Nilxis. Those usually play well.

@GraceyManor The worlds you suggested are all large (2048x2048), and two out of three (Blue Bayou, Hope Springs) require several expansions.

Sorry! I was just trying to help.I don't have all the expansions and the Blue Bayou listed only base game and I never noticed anything missing.
And one person's small" is another person's large. -shrugs- I'll pay attention next time.Or I just won't help.

"GraceyManor;c-17448608" wrote:

"Turjan;c-17448603" wrote:
Go with AlexaKry's suggestion and look through the offerings by Riflong 7/13 or Nilxis. Those usually play well.

@GraceyManor The worlds you suggested are all large (2048x2048), and two out of three (Blue Bayou, Hope Springs) require several expansions.

Sorry! I was just trying to help.I don't have all the expansions and the Blue Bayou listed only base game and I never noticed anything missing.
And one person's small" is another person's large. -shrugs- I'll pay attention next time.

The Blue Bayou description reads: "Requires Riverview, and all expansions including Generations plus Fast Lane stuff pack." Or "Ten Late Night clubs".
I know you wanted to help, but I thought I'd point that out.

"StephSteb;c-17448613" wrote:
Yeah, sorry guys! I saw "small world" and got excited to tell everyone about Positano, heh.

:D That´s ok, it is a nice world, @StephSteb !

It's okay. Remmo made beautiful worlds. :)