Am I correct or not? Opinions please.
Both kill orders are correct since it's not like there is a mechanically predefined kill order. Interestingly, every server/faction seems to have its own "default" kill order that people have come to expect (which was an adventure when the server merges first happened and you had to explain what "doing this the usual way?" meant to people with different interpretations of it thanks to learning it on different servers).
The kill order I always default to is right>left>middle (making sure to mark them before we start). None of the bosses deal all that much damage, even if you're appropriate geared for it, so the only really "dangerous" thing is the big guy's pin. When he's down, it doesn't really matter what the other kill order is because the remaining 2 have the same amount of hp and you'll still deal with 1 that ignores threat while you're killing the second with the last one responding to threat regardless.
While it doesn't really matter to me what kill order is used, the one thing that *always* perturbs me is when someone runs up to the upper platforms: inevitably, they'll be the one called out resulting in the 2 untauntable bosses running all the way up there (and potentially back down if the rail person isn't inept and knows to take the fall before they're jumped and pinned) which splits the group up and cuts down on the damage the group is throwing out (even if you're burning the center boss first, it still reduces damage output because you're not benefiting from incidental AoE). Don't bother with doing the rail/platform thing. Just stand in the center with everyone else and burn the bastids down in whatever kill order the group decided on beforehand.
Also, when the adds spawn after one of the bosses dies, stay grouped up so that you can burn those adds down faster. It's also a bad idea to use your knockback on those adds: they die crazy fast if they're all together and using a KB just spreads them out and makes them take longer to die (I often see healers running around like crazy or using KB as soon as the horde gets close which is *so* annoying; even if you're in recruit gear, they barely tickle and you're just making it more annoying for your tank to pick up all of them and your DPS to burn them down).