Pick your poison...
DNP is a toxic substance that although may be tolerated well by some, there is almost no studies on it for humans and let's say the way it litteraly "burns" the fat with heat production is not very natural and my guess is when you take that shit your body is filled up with free radicals that damage most cells in your body...
Clen or ephedrine, pretty safe in moderate dose, but the way it burns fat is thru increased calories expenditures by increasing HR. Also increases core temperature and metabolism by activating beta-2 receptors.
T3 increase whole body metabolism: accelerate the uptake of nutrients in the cells, increasing the the consumption of stored glycogen, fats, and also muscle.
I personally believe T3 is relatively the safest choice, in moderate amount. Must use some aas with it to keep muscle loss to a minimum. If you use it with a correct diet, training and aas you can get extremely lean with it without the use of DNP or clen/ephedrine which put heavy strain on the heart already taxed by aas and heavy training. Just my 2 cents