While I'd usually favor spells with bigger AOE claiming that in most situations it should make up for the lower single-target damage, in some cases the AOE simply is too big and is thus wasted most of the time. Arcane orb seems more powerful since it simply has big enough AOE to hit a very large portion of the monsters I usually see on my screen and deals more damage to each of them compared to energy twister, while energy twister would rarely hit more monsters than arcane orb (even though the max number of monsters it can hit is higher), and often even hit less monsters than arcane orb!
Actually similar stuff can be said for seismic slam and hammer of the ancients - The former has a much greater AOE, but then again with either 1.5X fury cost or only 77.5% of the damage (depending on rune) it has a hard time to compete. Though in this case it's actually situational as for which is better, while in the energy twister case it's really no-brainer that most often arcane orb (and thus most likely many other spenders, since I assume arcane orb isn't the end-all-be-all spell that everyone will use) would just win out.
The only hope for energy twister is if the rune effects make it easier to manage (aka do more focused damage and have less of a "specific-situation-requirement" to be effective).