Actually yea, I'm quite fond of both the Force dragon and the Prismatic dragon. If I had to pick a favorite of the two...............
hm.. Maybe the, No, Prismatic dragon. defiantly prismatic.
Of course you had to go straight for the Epic-Level ones... I'll see what I can do.
Edit: Darn unique Breath Weapon. Oh, and if you have an Prismatic Dragon Lineage Draconic Legacy doesn't do squat until 23rd level. HD limit and all that.