Water, a little squirt of Dawn, a little LemiShine. Don't go to heavy on the LemiShine or it will discolor your brass. One article on the Accurate Shooter bulletin tried a bunch of combinations - I can't find the link though.
I soak my brass in hot water (2 qts.)with a good squeeze of Dawn Dish Soap and 2 table spoons of Citric Acid. Shake well and let it soak overnight. rinse well with clean hot water. Towel dry and then blow dry with a hair dryer. This will clean about 50 rifle cases or 100 + pistol cases at a time. Since I'm retired I have lots of time and very little money so this process works for me.