A stainless steel sink will be noisier when running the disposal. I've got a SS undermount sink on a granite counter. For a drop in, I think maybe the CI sink would be better. I really like the undermount - it makes brushing counter stuff into the sink so much easier. Keeping SS looking nice might be an issue, but is possible unless you pick a polished one (those a nearly impossible to keep shiney - too easy to scratch and they show water spots). A CI sink is more likely to shatter your glass that slips than a SS one. On a drop-in, though, the large lip is a pain, but the SS one is always messy as it is hard to keep the edge clean at the counter junction.