There is no such thing as the perfect deer cartridge. No matter how hard you try you can't lump cartridges into a "one size fits all" group because hunting situations, terrain and personal preferences are just too varied. That is one reason we have so many factory chamberings, not to mention wildcats. There are a few cartridges that come close to being ideal, but none perfect. The first that comes to mind is the 7mm-08 with a 140 grain bullet. Light recoil and it carries a slight advantage over a 150 grain bullet from a 308 Win past 200 yards. Although the 308 Win is a fine cartridge in its own right. So too the 243 Win, 270 Win, 260 Rem, 6.5X55mm, 280 Rem, 25-06 Rem, 30-06 Springfield, 45/70 Govt, 444 Mar, 450 Mar, 250 Savage, 300 Savage, etc....