Really hard choice. All three are wonderful and worth buying. In the end I voted for Gold man because it's the biggest, with the idea if one is to have an Amouage, he may as well go all the way and get the most powerful (that is, Gold man, or woman, or Ubar). Perhaps for this reason, though, some people find that Gold is difficult to use because too powerful; not me.
It doesn't remind me too much of Derby. Gold has a lot of incense, thick flowers (tuberose, rose and what not), and is just bigger. I agree that Jubilation XXV, while perhaps the best in the incense category, reminds one of other clean incense perfumes (from Timbuktu on). Epic is a beautiful rose-oud-wood, and, again, there are now a few ouds around. I didn't know that it is less expensive. Are you sure that you are not comparing different sizes?