The strings should have NOTHING to do with your decision on buying a guitar. You could just change them (which you often will anyways). As far as the 2 options go though, I say nylon are easier to learn on. This is only because they are easier on your fingers. It will hurt more to play on steel since your fingers aren't used to it and haven't developed calluses yet.

Sound is all preference. Steal gives you a sharper/brighter tone. Nylon gives you a softer/dull sound (not dull in a bad way, but I can't think of another word to use). You shouldn't be too worried about your sound yet though, since you are just learning.

So I'd say go with nylon right now. Hands down easier for a beginner. Don't be afraid to try steal though. Its just a little harder on your fingers.