I believe that it's a matter of physics that the longer the scale, the more sustain you are likely to get. Playing a D note, for example, is likely to produce the same tone on a 17" scale tenor as on a 20" scale baritone or a 24" scale guitar. However, some of the sound qualities, like sustain, are going to be affected by different scale lengths. I play a lot of baritone ukulele, and to my admittedly subjective ear, a tenor ukulele sounds more percussive (i.e., less sustain) than a baritone ukulele, which sounds more percussive than a 23" scale tenor guitar with nylon strings, which in turn sounds more percussive than a full-scale nylon string guitar.
I also have a steel string tenor ukulele, a steel string baritone ukulele, and some steel string tenor guitars. These instruments sound, to me, somewhat more like guitars because I tend to think of steel string acoustic guitars when I think of guitars, possibly because I grew up listening to 60s and 70s pop music, much of which favored steel string acoustic guitars, rather than classical guitar music. One possible option for a guitar-like sound, given your decision to limit scale length, would be to find or custom order a steel string tenor ukulele tuned DGBE.