It's kind of a silly comparison. Halo, is a world, a universe, philosophy ,existentialist ideas, science fiction and fantasy. It has inspired, games, movies, novels, debates, events, toys, and Halloween costumes.
Grand Turismo is a perfectly fine racing game, but who dresses up like that for Halloween? And the move with Clint Eastwood was nice, but I fail to see how it ties into the game. There are almost like no races.
If you are asking which one helps sell more consoles. I think we will have to wait until the Xbox Reveal, and see if Halo gets as much mention as Grant Turismo did at the PS4 event.







