Let's see... I'm a bit of a pessimist, so let's tally the downsides of each setting.
Pollution:
Steampunk: Unless we're doing a steampunk setting where magic and technology coexist, the air quality is going to be pretty bad from burning all that coal.
Cyberpunk: Probably less air pollution, since we've likely transitioned to nuclear power by this time, but the pollutants that do exist are probably going to mutate you into a horrific abomination if they don't kill you outright.
Point - Steampunk
Medical Technology:
Steampunk: Getting an internal organ or a limb replaced by a steam-powered one sounds cool on paper, but I think having my apartment fill up with carbon monoxide when I'm trying to type on my manual typewriter is going to suck balls.
Cyberpunk: Cybernetics, genetic engineering, compact power sources. What's not to like.
Point - Cyberpunk
Bad Stuff
Steampunk - Giant rats, maybe? Heavily armed gangsters? I have no idea.
Cyberpunk - Aforementioned abominable aberrations. Not to mention nerve gas, genetically engineered super-viruses, unstoppable armored killing machines, and RADIOACTIVE giant rats. Good lord.
Point - Steampunk.
Food:
Steampunk - Pretty much standard stuff, assuming you can afford it. Given the dystopian setting for most steampunk fiction, that seems unlikely.
Cyberpunk - "Eat Recycled Food! It's good for the environment, and okay for you!"
Point - Steampunk.
So it looks like the winner is Steampunk for me.