They all seem to do the same thing...
Break up salt buildup in hydroponic watering systems.
Off first glance, I would imagine florakleen or ataclean would be best bets.
I'm not a hydro guy and have no experience with these products, just my two cents.
Drip clean is almost twice the price of Florakleen, but since I'm already using H&G nutrients, should I still go for Drip clean?