I've been a .30 caliber/180 gr bullet fan for elk ever since I shot my first bull back in 1966. I shot that first bull with a factory load, but all of them since have been with handloads. When I used a .30-06 I had good results with 180 gr Sierra GameKing bullets. For 20 some years I shot 180 gr Nosler Partitions in my .30 Gibbs, and the first two bulls that I killed with my .300 Weatherby were one with a 168 gr Barnes TSX bullet and the other with a Barnes TTSX bullet. My elk load now with my .300 Wby is with 180 gr Barnes TTSX bullets.
The most important factor is bullet placement. I really don't think that any one brand of modern hunting bullets will kill better than the others. Try several different brands and bullets and see which one shoots best in your rifle, then use it and practice, practice, practice.