"Best" is always subjective, but all things considered, from the muzzle to as far as one can consistently hit, 45 Colt bullets designed by Elmer Keith or FN series Veral Smith always work on deer sized animals, small game or even larger. This has been done for nearly a century, even at traditional 45 Colt/ACP velocity levels or loaded to 32,000CUP for the last thirty years.
If one is shooting deer inside 40 yards, especially with a rifle, expanding bullets do provide more "shock" on deer sized game when hit in non-CNS areas over traditional solids. Throw in every bone in the critter and the bullets designed to splat don't make the grade.
The good news is one can make BETTER bullets for 750-2,400 fps range in our garage or shop....they can punch that 45 hole or even splat AND have some splash, even cut through any bone.
Generally if there are issues with non-obturating hard lead bullets, its caused by dimesional issues or finish issues in the gun. Are they necessary? Not for deer, but to disregard them is to leave potential on the table. Guys running unlubed bullets arent running soft, but they understand gun dimensions.
Plain old wheelweight metal, heatreated soft Hollow Points in a Keith or FN LBT will easily run well in a rifle. Witnessed it three times on Saturday.
