From my personal experience, the Hulda Clark Liver flush has been repeatedly and measurably effective, when fairly strictly followed. The benefits have far outweighed the inconvenience of the 18 hour process, 8-10 of which are spent sleeping. The worst part for me, is the taste of the Epsom Salts, which are sold over the counter as a laxative. I've found that the better alternative is to purchase Epsom Salts in capsule form http://drclarkstore.com/magnesium-sulfate-usp.html rather than to drink the Epsom Salts dissolved in water.
I'll admit, however, that I have not evaluated any of the other protocols that are out there. I just happened to start with the Clark protocol and it resolved my issues and provided some unexpected additional benefits.