Favourite bullet?
Favourite Copper Bullet??
Well there will be no definitive answer.
Are you are shooting CWD sized game, or large Wild Boar, Big Red stags or big game overseas - chances are different bullets will be more or less suitable.
Typical range you are shooting at, and muzzle velocity bullet will be launched at. Again impact velocity has a huge effect on what works.
Point of impact - if you hit the HILAR animal will drop on the spot abd be totally dead by the time you get to it. Put a bullet tight in behind the shoulder through heart and lungs it will jump and then a headlong run for a few seconds before piling up and will be totally dead when you get to it. Choice of bullet may well affect where you should put the bullet, but provided it is tough enough to penetrate to the vitals end result will be pretty similar. However a light rapidly expanding bullet may not penetrate the shoulder blade. The animal will be stunned, fall to the ground but then run off.
Rifle - every rifle seems to have its own idea as to what it likes.
What is available - there are lots of choices on the interwebulator, but many may well not be available to you because of geographic locality. What does your local reloading supply shop actually stock?
And finally, don’t forget that most of us won’t use every different type of bullet. We will try one or two and if they work then we stick with them. We will then recommend those to any one who asks.