I like the original pick of the 6.5-06, 338-06, and 375 Taylor.

The 6 I would toss would be:
.35 Remington - very little factory loaded ammo available, other better cartridges in that class, such as .356 and .358 Win and .35 Whelen.
8mm Remington Mag. - Doesn't seem to have caught on too much in this country.
325 WSM - really don't see a point in having that cartridge when the .300 WSM will do the exact same thing
7mm SAUM - the WSM's over power it (popularity)
300 SAUM - The WSM's over power it (popularity)
25 WSSM - Sure it equals (supposedly) the power of the .25-06, but where does it have any advantage over its longer kin? I really don't see it.