I agree with the others that Sewer's Aid (they sell that at JAF, too) is the best option for conditioning machine thread. It is a liquid that comes in a small, clear bottle.
I tried Thread Magic 2 years ago for hand work before I tried beeswax. Then I lost the thing & the LQS I was already at buying fabric charged so much for Thread Heaven I just bought a thing of beeswax. My personal preference is for the beeswax, but I'm sure I'm in the minority. Part of that preference is that I have a lot of chemical sensitivities, so I try to stick with natural products as much as possible.