Continental sell more tyres in South Africa since they do the most advertising.
In the years of driving and my business owing (over 60) cars and vans, the road grip story has never been a problem, they all seem to do their job admirably, dependent on the design of the suspension. For instance, Golfs and BMWs are excellent, Honda less so and at the bottom are Nissan LDVs
One thing, apart from the longevity of tyres (again, dependent on the driver) is tyre noise. Michelin are by far the best in terms of quietness, long life and sturdiness (don't mind bring driven up kerbs). However, we found about 8 years ago that some Continental tyres were irritatingly noisy above 100km/hr, the Chery were even worse and we had two Chery tyres that delaminated, one spectacularly so, the driver thought he had hit something large.
I agree that you get what you pay for, but why pay an extra 15% for the same Yokohama tyre at a "premium dealer" when you can get it at a tyre discounter? They might not have a swanky showroom with free coffee and a TV, but the tyre and fitting is the same