.3-.4 sec (CoD kill times)
.5-.7 sec (Destiny Y1 kill times)
.8-1.0 sec (Destiny Y2 kill times)
I always like longer TTK because it allows people to get in lengthy gunfights rather than just seeing who has the quickest reflexes.
I'm fine with all of them. I play hardcore in CoD and Battlefield. And I play Destiny. I used to play the previous Halos on last gen as well. I do well with any ttk.