While being "the best" doesn't always lead to becoming "the most popular", being "the most popular" almost always leads to most options and wider distribution for the consumer.
I like the 250-3000 and 257 Roberts, but wouldn't recommend either of them in lieu of the 243 to the casual hunter. While the 223, 22-250, 243, 25-06, 6.5CM, 270, 7mm RM, 30-30, 308, 30-06, and 300 WM might not be the best cartridges in their respective market niches, they are close enough, good enough, to be the most popular cartridges in their respective market niches.
