Daemons and Titans are the easiest things to kill that drop cache, and drop rate is 1% regardless of mob strength. The problem is finding a spawn that is fast enough to keep up with how fast you can kill them.
I kill daemons in Wind for cache maps, but since you are looking for supply and cache, I would suggest the Titans in Despise L3. There are also a bunch of Cyclopean Warriors that spawn with the 2 Titans down there.