I like the sound from a brass bell, I have two, one looks like this
one, but it's still sitting in my bike bits box as it was too narrow to fit one my main bike (keep meaning to try it on another bike), the other one is similar but with a different fitting mechanism to the bars.
I like the sound a brass bell makes, not too loud and a pleasant sound. I have found in the past that bells with plastic bits don't seem to suit me as the plastic bit has been the weak point, whereas that brass bell has now been on my bike for about 4 years I think.