Guitar?I have a steel- string, but prefer nylon.:)
Steel string 4 playing wid plectrum, nylon 4 finger style playing
I like the sound of steel better, sweetie! But nylon is nice too, especially if you wanna play, but you don't want to disturb others!
As people say, nylon strings are (generally) for classical/spanish acoustic guitars - put steel on those and goodbye guitar; the neck will bow and can break.. On other guitars then steel is what you need - if you put nylon on you will have no sustain and tonality. A reasonable guide is the string winding mechanism of the classical guitar. Actually, steel is a pretty much generic term as lots of steel strings are now coated or wound with bronze or phosphor-bronze etc. Strings also come in different gauges or thicknesses depending on what you play. Lighter strings are best for finger-picking and heavier for strumming. Electric guitar strings tend to be strung lighter than acoustic. Finally, a guitar is built for a certain string gauge. If you put strings on that are too light then you may get fret buzz but if you put strings on that are too heavy you could bow the neck of the guitar.
Steel string. More resonance, better sound quality and control.