My wife and I have debated this "how to signal responsibly and non-offensively?" issue over the past decade, it seems. She's firmly in the voice camp. She thinks that bells are irritating and not specific as to the rider's intent.
I like the gentleness of the bell's 'ping', and feel that the ping is a unique sound that emerges from the clutter of everyday noises. I don't have any bells on my bikes at this time though.
I asked an acquaintance at church just yesterday about her preference. She prefers voice over bell.
EDIT: I forgot to add that I'd prefer to ride where I don't have to interact with pedestrians at all, but that's not practical when you live in or nearby a city. The available riding corridors naturally collapse onto a multi-use path from time to time. It's an unavoidable reality.