I pulled this off of www.chuckhawks.com It is not my own info, nor opnion:
"What follows is a list of centerfire rifle cartridges. These are the cartridges whose articles have gotten the most page views on Guns & Shooting Online during the last complete year for which I have statistics. These are the cartridges in which the greatest number of you, the readers, have been most interested.
1. .308 Winchester - The .308 is one of the best selling cartridges in North America and the world (#5 on most lists), so it is no surprise that it interests many readers. It is the premier all-around cartridge for short action rifles.
2. .270 Winchester - The thousands of page views garnered by my article "The Great .270 Winchester" shows that interest in this classic all-around cartridge remains high. It is #3 on most North American sales lists, and it is popular all over the world. The .270 has been the standard of comparison for long range hunting cartridges for three quarters of a century, and it may be the best balanced all-around + long range hunting cartridge ever devised.
3. .30-06 Springfield - In sales, this is the most popular hunting cartridge in North America, and it is one of the elite worldwide cartridges. Many experts regard it as the best all-around hunting cartridge in the world. The .30-06 is in use on every continent where big game is hunted, so it is no surprise that its article gets a lot of page views.
4. .45-70 Government - The interest shown in this cartridge by the readers of Guns & Shooting Online came as quite a surprise. My article "The Good Old .45-70" must have been well named, as it has gotten a great many page hits. The .45-70 is, indeed, a very good old cartridge, and the most popular big bore in North America.
5. .30-30 Winchester - The .30-30 is one of the top selling rifle cartridges in North America (#1 to #4 on the sales lists, depending on which list you read). Interest in the cartridge remains high, probably partly due to its romantic association with the Old West, and partly because it is one of the best 200 yard deer and medium game cartridges ever designed.
6. 7mm Remington Magnum - The 7mm Rem. Mag. is the most popular belted cartridge in North America, number 7 on most ammunition sales lists. It is a fine all-around cartridge, deserving of its world-wide popularity. So it is not surprising that my article "Long Range Power: The 7mm Remington Magnum" regularly gets thousands of page views.
7. .223 Remington - This cartridge owes its popularity to its adoption by the USA and NATO as a standard military round. But it is also a fine, accurate, varmint cartridge and a pleasure to shoot at the range. Ammunition is widely distributed and inexpensive. The .223 (5.56mm NATO) is #2 on most sales lists and the top selling .22 centerfire rifle cartridge in the world.
8. .270 WSM - The .270 WSM has apparently taken the lead in the short magnum sweepstakes, at least among the readers of Guns and Shooting Online. This is not a surprise, as it is probably the most useful of the breed, and the only one that isn't simply a duplicate of another cartridge.
9. .300 Win. Mag. - The world's most popular .300 Magnum is the Winchester version, which is in the top 10 on most sales lists. This popularity is evidenced by the strong interest shown in this cartridge by Guns and Shooting Online readers.
10. .243 Winchester - The .243 is one of the lightest recoiling, long range, medium game cartridges in the world. It is also a capable varmint cartridge. The .243 is a very popular cartridge worldwide (number 6 on most lists in North America). It deserves the interest that its article receives."
Hope this helps.