#1 Ayrton Senna (McLaren) and Alain Prost (McLaren and Ferrari)
This rivalry is regarded one of the best and, most fierce in the history of Formula 1. Both of them are regarded as one of the finest and, best drivers in Formula 1.
Alain Prost joined Niki Lauda at McLaren in 1984. Lauda won the Championship in 1984 and retired. Prost dominated the next season and became the first French driver to win the World Championship in 1985 and, won it in 1986 as well.
1987 was a bad year for the Frenchman as he came 4th, falling behind Nelson Piquet (Champion), Nigel Mansell and Lotus driver Ayrton Senna. McLaren signed Senna from Lotus in 1988 and this was when the famous rivalry between the two McLaren drivers began.
Prost had himself convinced McLaren to sign Senna on a 3-year contract. The Frenchman finished 1st or 2nd in almost all the races that year but, the Brazillian ended up winning the Championship that year. Prost launched a complaint to McLaren that the constructors were giving preferential treatment to Senna.
Although there was mutual admiration between the two, in 1989, the battle for supremacy turned this into one of the most fierce rivalries in the history of any sport. The rivalry became so heated that Prost accused Senna of "dangerous driving". Both these drivers were involved in a famous collision in the Japanese Grand Prix as well.
In 1990, Prost signed for Ferrari, teaming up with the Englishman Nigel Mansell. The rivalry still continued between Prost and, Senna and moreover, this time it was a rivalry between Ferrari and McLaren as well. Senna collided with Prost, ruling out both the drivers from the race. By doing this, the Brazilian successfully won the World Championship.
Senna won the Championship again in 1992, and Prost won it in 1993. The Brazilian was involved in a famous car crash in 1994 and, was killed during the San Marino Grand Prix. The Frenchman retired in 1993 as the driver with the most number of Grand Prix wins.