I usually play crucible and use snipers in my special slot.
I use kontrol freeks, a long one on my aiming stick.
Also I play on a 24" monitor
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As I'm sure someone else has already said, The one that feels right to you. There is no definitive 100% correct answer for this question as play styles and reflex differ greatly from player to player. Experiment until you find something the feels right and go from the there.