Strings
String brands in stock
Aquila
Oasis
Worth
Ken Middleton's Living Waters Strings
Kamaka
Pepe Romero
D'Addario

There is no greater personal preference choice outside of the instrument than the strings.
Your personal playing style can heavily influence your preference in strings.
Also your instrument, some instruments will like one string better than another as the biggest part of the sound and tone starts with the string.
There are a lot of string choices in a lot of brands.
The basic styles or types of strings are synthetic gut and fluorocarbon AKA "Carbon"
The traditional Ukulele strings were "gut" strings and like many other stringed instruments, literally made from animal gut.
But as with other instruments gut is fussy, inconsistent and harder to get along with.
So synthetic gut strings were developed, mostly made out of a nylon like material.
More recently people have started selling fluorocarbon strings which are basically monofilament fishing line.
Synthetic gut strings are usually warmer and very natural sounding and some are way better than others.
Fluorocarbon are brighter and some say clearer.
The big advantage I've seen are in Baritone and some Tenor sets where nylon strings use 1 or 2 wound strings on the lower note(s) (bass) strings.  Fluorocarbon strings are usually all unwound.
Many people really don't care for the wound strings, myself included. Some feel they are not balanced sounding to the gut strings in the set.
Fluorocarbon strings are also thinner in diameter than gut strings and can feel like they are higher tension than gut. Some like them others don't.
We sell Fluorocarbon strings from Oasis, Worth and Ken Middlleton's Living Water Strings.
 
My personal favorite strings (so far) are Aquila "Sugar" strings. Kind of the best of both worlds. Warmer, richer and thicker than fluorocarbon and brighter, clearer and seem to stay in tune once settled better than gut strings. Aquila "Reds" are another unique string choice, they are very musical and have a beautiful sustain, resonance and  decay.
 
One more note on strings. The standard tuning on Ukuleles are with a "High G string". You can also get sets in many strings with a "Low G string" which give a much deeper and warmer sound. Keep in mind many "Low G" sets come with a wound "G". So you might want to consider fluorocarbon sets.
 
Aquila Sugar string information can be found here
https://aquilacorde.com/en/shop/modern-instrument-string-sets/ukulele-banjouke-en/sugar/
 
Aquila full product info can be found here
https://aquilacorde.com/en/modern-music/ukulele-banjouke-strings/

Oasis fluorocarbon  string information can be found here
https://www.oasishumidifiers.com/product/ukulele-strings/
 
A really cool video of Sugar strings
https://www.youtube.com/watch?v=pIRLdhsOpR8&list=PLu-b8VtUnNsVTHRwbQZPBW9JoxXiG3Hi0&t=9s