In all cases, I favor increasing dUtility/dWork. Currently the utility gains to the poor from increasing work are nearly flat, and often negative. Note the graph in this post, illustrating the disposable income gains both with and without transfers:

http://johnhcochrane.blogspot.co.uk/2012/11/taxes-and-cliffs...

Replacing welfare with work would increase this, since incomes would go down without work. In contrast, taxing anyone (rich or poor) would decrease dUtility/dWork. Unconditional wealth transfers also decrease dUtility/dWork due to diminishing marginal gains.