I am in the process of changing every string in our program to the new KIDS strings, for instructional purposes. It is amazing how fast I have become in the process now that I have changed over 100 sets of strings! You can see my thread on those strings elsewhere.
This evening, I grabbed my "old" Makala CE (purchased January 2016, my oldest ukulele), and played it for a while. I simply wasn't enjoying the Aquila Super Nylguts that were on it, and had a pack of Martin 600s around, so I changed my strings. It is like having a whole new instrument.
I'm not going to get into string wars, but I have found that I am a fluorocarbon guy. I love the colored Aquilas for my students--for educational purposes, but for my ukuleles, I like the Martins, which I understand are very plain fluorocarbons. I do need to find out what other full fluorocarbon solutions there are for my Opio, which comes with the stock KoAloha. Nothing wrong with the stock strings...but replacements from the company are $8 plus shipping where the Martins can be purchased for less than $6, shipped.
At any rate, I'm changing strings right now because of preference versus need. My Rye Rabbits on my Outdoor Ukulele didn't last long before one of them frayed and broke--so there are Martin 620s on that ukulele right now.
Thank goodness strings are so (relatively) inexpensive.