I have not used a controller or played Halo 5 in a long time and my aiming feels off, any tips for the controller and what is the best sensitivity?
The best sensitivity is one that you yourself are comfortable with.
Set it low enough you are hitting about 55%+ of your shots. Then you can increase it over time if you need to. I play on default and do just fine. A bunch of pros do too. Most don’t play on it too high as it’s too hard for most people to be consistent with it and the trade-off isn’t worth it.
You can choose the sensitivity in which you’re more comfortable dude, but, I recommend you to have a low acceleration and dead zone in zero (0%)