Top BM logs for EN (Mythic):
https://www.warcraftlogs.com/ranking...c=BeastMastery
- Shows Killer Cobra clearly being better, there are some uses for Stampede on Il'gynoth and Xavius because of the sheer amount of adds.
Top BM logs for EN (Heroic):
https://www.warcraftlogs.com/ranking...y&difficulty=4
- Shows Killer Cobra top across the board.
Top BM Logs for ToV (Heroic):
https://www.warcraftlogs.com/ranking...y&difficulty=4
- Showing Kill Cobra top again, with some outside cases on Helya, again due to masses of adds, the same is true for the ToV Mythic logs but there aren't any Helya M kills with BM hunters yet.
As for the original question, don't use Cobra Shot in your normal rotation unless you're above 90 focus, you want to pool as much as possible. Go into BW with as much focus as possible, paying attention to when DB and KC will come off CD. Then you simply KC > CS and use DB when it comes off CD.