I was thinking about steel since that is what it had originally (when it was a mandolin and also when it was a banjo). But I decided to go with Worth extra-hard polymer nylon strings, in part because it would put less strain on the modified neck and also because I just like the sound of nylon. The instrument doesn't offer the best sustain but it has a very unique sound. It will be enjoyable to get to know this uke in the months to come and to try to figure out what sounds best. Right now, the percussive nature of clawhammer banjo style is by far the best sound--very balanced, fast attack, great volume. So maybe that is the way to go....