No bullet is absolutely great, but why are coppers not absolutely great? Well their BC's are in the toilet and they're harder on barrels than lead is, they're more expensive than lead are, to some people copper solids don't work as well as lead and that could be due to them using to heavy of solid.
On the flip side TTSX's have been great for me an my buddy. Between me, him and his son we've got 23 animal 16 deer, 5 bears and two elk all but 2 dropped where they stood. One Mule deer was shooter error and one bear was shot while he was running down hill, the bear was hit in the
but had momentum and finally balled up about 50yds from where he was hit, the deer didn't go very far maybe 10 to 15yds. And yardage ranges from 100 as far as 720 being the furthest kill on a mule deer. Here's a pic of the exit hole from the deer at 720yds, 300wsm and 150 ttsx with a muzzle velocity of 3400fps, he said the rock behind it was painted red with blood. So the ttsx's work for us.