This is one of those "Goldilocks stories" of going through many sets of nylgut, nylon, tied-end as well as ball-end classical strings of varying tensions.
The Aquila strings that were 'intended' for use on the guitalele (and tuned a perfect 4th above standard guitar tuning) snapped on my during the first few hours of play.
D'addario classical strings worked okay, but the standard tension was too loose and rubbery, and the hard tension set was brutal on the fingers at the higher pitch.
These are perfect. I had them tuned to the '4th above rule' - ADGCEA, but the high A felt a bit too stiff.
By lowering the pitch a half-step to G#C#...., I found the perfect balance.
The ball ends on these worked out perfectly, and yes they took a few days to stretch out, but they stay very stable during play. They're also very reasonably priced.