While it may be true that conventional landfills are worse for the climate, the jury is still out on that, and no credible studies have been done.  We DO know that there's a 3rd option that beats them both: a "zero waste" system that avoids incineration, keeps organics out of landfills through composting, and biologically stabilizes any residuals that go to landfills, so that the methane production is done in a digester system that can capture it all before landfilling the digestate.  See more at www.energyjustice.net/zerowaste and www.ecocycle.org/specialreports/leftovers