I had also tried a bunch of different flare tool kits with varying success...
Finally ended up with a Brakequip set (in a red box) and it is by far the best I've had, it works really great.
I've also used the kit John speaks of and it is either the very same make/quality or nearly as good.
Looking on the Brakequip site the tool has changed a little from the one I have but I expect it is still very good, now in a purple box.
http://brakequip.com/products/tools/flaring-tools/I have not checked the prices lately but at the time I purchased Brakequip was the best value when purchasing direct, and even better pricing when buying several kits (your friends will want one too).