+3 or 4 for the 6-284. WAY better brass than the other two (Lapua does make 30-06 brass but you will have to turn the necks & that sucks
powder capacity wise, they are all pretty much the same, the shorter fatter case design of the 284 will lend itself to a more efficient powder burn & allow you so seat the boolets out farther, increasing internal powder capacity. According to Sierra, the 6-284 has set a world 1000yd benchrest record with the 107smk. Don't think the wby or '06 can say that.
On the other hand, from what i'm told, the '06 is a good bit easier to get to feed properly. If you run a center feed magazine, you won't have any issues with the 284 either.
Weighing the pro's & con's of all three, I feel the 6-284 has more to offer than either of the two in question.