~~~ Premise ~~~
I don't think the vigor with which friends, family, and the internet have proselytized cloth diapers matches with reality.
~~~ Cost ~~~
Walmart brand disposables range from .10 to .17 cents per diaper, say an average of .14. We use about 12 a day so it'd cost $1.68 a day or $615 a year.
Let's say you inherited your cloth diapers for free (I did, but looking up the full set of green mountain diapers I have it probably cost over $400 with accessories)
We run loads of 24 diapers so we'd have to do about 180 loads a year. As a very conservative estimate let's say it costs us $1 per load (we wash on hot + extra rinse + add oxyclean to get the stink out) (we don't own a dryer which would bump the cost even higher).
So best case scenario you get your diapers for free and you do laundry super cheap so you do 180 loads of laundry to save $435 a year. Doesn't seem like a great deal.
~~~ Environment ~~~
Stuff in landfills doesn't matter, carbon emissions DO matter.
It's hard to find exact numbers but
one study I looked at came out to .2 lbs CO2 per disposable. That comes to 876 lbs CO2 per year for us or the equivalent of 44 gallons of gasoline.
Emissions from doing laundry vary wildly but the point is the amount of emissions prevented vs the labor required has to be vanishingly small, if not possibly negative for the most wasteful launderers.
~~~ Conclusion ~~~
Cloth diapers are definitely cheaper and usually better for the environment. If you're a hardcore environmentalist penny pincher who does cloth exclusively I salute you, but it's hardly a slam dunk (I still do about half cloth anyways).