I've never lived in Boston, but I've lived in SF and current live in the Valley and I have to say that SF is awesome for public transit (when it's on time) and

I've never lived in Boston, but I've lived in SF and current live in the Valley and I have to say that SF is awesome for public transit (when it's on time) and SV is better for bike because of the bike lanes. SamTrans on the peninsula is a joke, but the VTA and CalTrain are pretty good. They don't have the extensive coverage of Muni in SF, but if you aren't willing to walk a few blocks to get from a transit stop then you need a car.