Either of them produces a nice finish when applied properly. I do have a strong preference for the Flex Coat Lite though because it is a thinner finish with less build up, and it doesn't need to be heated to penetrate like the Duragloss or standard Flex Coat.
And as Steve mentioned, using thin coats produces a much better finish than think coats. Also, I have found that if I mix up a new separate small batch of finish for each section of the rod, it results in a much nicer finish because it doesn't have time to thicken before you're done applying it. Applying the finsh while the rod is rotating on the drying motor (as Steve mentioned) is also very conducive to having a good finish and produces fewer bubbles because you drag the finish over the thread as the rod rotates instead of brushing it.