Like most folks I started with corelockts after one penciled through a doe at 60 yards I switched to the brand new ballistic tips and started reloading. So far I've used NBT's, accubond, partitions, and Barnes TTSX on elk. The ballistic tip that turned into shrapnel on a big bull convinced me to go with the Barnes. My sample size is not scientific evidence but I'm convinced that on an animal that can go over 800 lbs. like a Rocky Mtn elk, that tougher bullets that can break bone and penetrate a long way are worth a premium of a few extra dollars.
I'd be content with most bullets for deer sized game and really prefer the BT for that DRT factor but elk are a different ballgame. We tend to hunt within a couple of hundred yards of a public / private boundary so stopping them quickly is important to me and the TTSX has done that in my experience better than any other bullet.
