How much DME do you guys like to use for carbonation for a 5 gallon batch?
1 1/4 cups in 2 cups boiling water.
Measure it according to how much wort you actually will prime, as brewers rarely wind up with five gallons. One quarter cup per gallon of wort.
It varies depending on the amount of carbonation you want (by style) and temperature.
Here's a nomograph to compute the amount of sugar.
Then multiply the sugar quantity by ~1.7 to get the amount of DME to use.