In my experience Ballistic Tips and Accubonds produce fine accuracy in my rifles. I wonder though why you are more concerned with accuracy rather than with terminal performance. The accuracy of a big game rifle, within practical limits does not need to precise, the target is large and few hunters can shoot up to a 2 MOA rifle on demand under field conditions.
But when we study terminal performance we see that not all bullets are created equally. You can choose the performance that is best suited for the game you intend to hunt, over the range you intend to shoot, and for the velocity of your load. For example, BTs open quickly and violently where TSX's penetrate deep and retain much of their original weight. Where a BT might be a good choice for shots at long range on light game that offers little resistance to the bullet, they would be a poor choice for your .270 if you stumbled over a grizzly hidden in in the willows whose coat is covered with ice and frozen mud. Having said that my son in law killed a Yukon moose this year, the range was short, his bullet was a BT and his rifle was a .300 Winchester. He relates that the wound volume from his second shot was foot ball size, but the first shot broke up on the shoulder.
My advice is to pick the bullet that is known to perform well on the weight of game you intend to hunt, fired at a velocity you intend to use, over the range at which you intend to shoot. Over normal ranges, you should choose mono-metal or a bonded core bullet if your rifle has a muzzle velocity in excess of 3000 fps.
Nosler Partitions have a good reputation on all North American game, but they are not be my go to bullet for big bears. Camp Cook on the other hand found they work just fine for big bears. Copper cup and lead core bullets work fine for most big game when fired from moderately powerful rifles, say with muzzle velocities up to 2800 fps, and often these bullets give their best performance with impact velocities of 2400-2500 fps. Cast lead bullets have a good reputation on game when the velocity is below 2000 fps, although depending on the actual velocity and the hardness of the bullet, you might find that there is little or no upset, so I prefer a flat-nosed profile.