Ben,
My perspective comes from prone shooting competition only, and therefore, this information will be dedicated to the heavier bullets.
Sierra's 107 has been my favorite choice at 300Y/300M. It shoots just as well as the Berger 105BT and 108BT. No diffrence in group size either and same X-count. This one is a no brainer.
Another choice for 300M is the excellent Berger 95 BT. It goes a little faster too, accurately. It is one of Norma's bullet choices. Can they be wrong ?
For 600 yds, the Sierra 107 does very good, with very good X-count. The Berger 105 and 108 BT will do just as well, with a very small edge to the 108. Under a 'good conditions' day, they will all achieve excellent and comparable accuracy. On a 'not so forgivng day', I will go with my trusty old Berger 105 VLD, touching the lands, end of story.
All my barrels are 30', 1-8' twist and .272N. Some are Kriegers 4 L/G, and some are Broughton 5R. All will shoot jut as accurate, 1/4 MOA. One of them has a Benchmark 27', 6 L/G, barrel that is not givng me the expected performance I hoped for. So far, it prints 1/2 MOA wih the Sierra 107s. I need more time with this one to figure it out, but time is always an issue. Which means, always go with the proven first. Then, if you have the time, and financial capabilities, go ahead and go crazy experimenting.
If you are planning to shoot matches, you won't go wrong with any of the above, Varget powder,29.5 - 30.0gr) and Fed Match primer,or CCI BR-4). Keep it simple, it pays.
Hope this helped some.
Andy