Not sure if the OP is still looking for information on this, but I have tried a number of strings now on this uke, and here are my findings from favorite to least favorite:
- Oasis Clear GPX Warm: Awesome sound. Warm tone with clear and airy sustain. Plenty of volume. A little stiff, but manageable even for beginners (such as myself). Love the sound from these strings.
- D'Addario EJ99T Fluorocarbon: Mellow and warm bell-like tone (despite the packaging saying they're bright). Good volume. Very comfortable to play. I like these a lot as well.
- Aquila Sugar: Lots of volume and very bell-like tone. They're a bit stiff and very squeaky depending on how dry your hands are. The sound is amazing if you can get past the squeaks.
- Fremont Blackline: Very bright sound. Almost like a harpsichord. Thinner feeling, but comfortable to play. I think I would like these strings better on a more mellow sounding tone wood like Mahogany.
- Martin M620 (Tenor): A little brighter, almost guitar like sound. I would say these are a good string to start with if you're getting away from your stock Nylgut for the first time to see if you like the fluorocarbon feel/tone.
- Aquila Nylgut: Everyone knows about these.
- Martin M600 (Concert): Experimented with concert strings to see if they were more comfortable. For me, I found the tension was almost the same, just a thinner line. Lacked volume and didn't provide as full a sound as the others.
If anyone wishes, I can make a video comparing all of them. Hope this helps!