Re: Winchester vs Lapua
The Lapua brass would "probably" last longer.
With that being said, some of the older Winchester brass was very good. The trick is, to find it in new boxes.
The Hoover family, some of the best shooters at the Williamsport 1000 yard matches, use the older Winchester brass in their 6.5/284 guns and have had better results with it then any brass they have tried and that includes the Lapua.
I have tried both (Winchester and Lapua) in my 6.5/284s and don't see a differance in accuracy in either brand of brass. Both brands hold up well in the smaller 6.5/284 case.
As per your 264 Win mag, you would have to try some of the Lapua and see for yourself which does the best and lasts the longest in YOUR rifle and caliber.