Whatever is on sale! The dishwasher does most of the work, and I can't say I've ever noticed an appreciable difference in the detergent I have use for the (rare) hand-washing task. I try to always rinse out my pots and pans while they're still hot so everything comes off easily; and if I need to soak something I usually throw some Simple Green in there and that works great. If something gets REALLY stuck (like burnt-on, or it somehow sat and got crusty) I will toss in a fresh dryer sheet and let it soak with that overnight - usually can just wipe it out the next morning.