I think this is actually how they imagined the genies. All three of them work together, when you look at it in a broader point.
Thundurus can Charge to draw from deck then discard with his attack, switch out to Landorus who can fish the energy back out from the discard and deal damage, then switch it over to Tornadus whos attack blows the energy over to Thundurus.
Not a pretty line up, since you got the setup attacks in between and are getting attacked in the meantime, which is why this combo would probably never work in competitive play (outside maybe a basic rush deck).
As far as which one is better, I'd say it's a bit early to count Thundurus out. Thundurus' focus is more for the open damager, as like others have already said, it can T2 for 80 damage, which against Stage 1s wont be enough to kill them (except Yanmega which would be OHKO), but it would still deal a great deal of damage, and if he survives can 2HKO almost any of the rest of the current meta's main attackers (minus Donphan due to resistance and pokebody reducing damage by half.)
Tornadus on the other hand can be used in almost any situation but in order to be as fast as Thundurus requires a DCE (which even with 4 isn't guaranteed in an opening hand or the first 2 turn draws even with supporters.) The resistance to Donphan is this boys main attraction as well as the fact that he lacks Thundurus' downfall of Donphan's resistance. Being able to 2HKO ANY of the current Meta attackers is nice, and the resistance to Donphan makes him viable for any deck.
So, sadly I would have to agree that in the broader view, Tornadus is better, but I wouldn't count Thundurus out as a viable opener. He has his places, and maybe later as the meta evolves with future sets he will see more play. But for now, my vote goes to Tornadus for his universal playability.