I'm in the early stages of building a solid body electric uke. It's in the style of a Stratocaster. I'm debating whether to go with steel strings and put in a mag pup or use nylon strings with a piezo rod pup in the saddle. Just wondering about the sound differences.
Obviously, the mag pup will give it more of a Strat look, but I could easily fake the look also.
I built a steel string tenor uke with a mag pickup a few years ago and have changed the strings several times, trying to get the same 'tight string' sound of a nylon string uke. The sound is good, but is a little harder on the ears, than the nylon strings. My current string sizes for the 17 inch scale length are G=12, C=17, E=14, & A=10. You have to have sharp angles on the strings at the nut and bridge so that they don't move around and buzz. I also use a steel threaded bolt for the bridge. I don't play any amped uke in public, because I am not a very good player.
Short scale instruments with steel strings often need higher gauge strings to enable tuning, and to reduce string tension, which makes it more playable too.
An alternative scale length that works great for ukulele tuning is tenor guitar. Scale length ranges from 19.5" up to where I like to build, 23".
Or change strings for other uke tunings.
If the instrument is intended for teaching, it makes no difference, the player will learn it as either.
If it's going to a steel string player guitarist, choose those.
Build it with player intention.
Steel strings will put more tension on the neck joint. Assuming you are not doing neck thru. Either way should be nice.