usually Charmander. Bulbasaur is probably technichally the best starter, and Squirtle is a good pokemon, but there aren't that many fire types, whereas grass/poison types are abundant, and pure water types are the most common pokemon in the game. So charmander is generally the best bet.
"Whether you like it or not, history is on our side. We will bury you." -Nikita Khrushchev, Soviet premier. Remark Nov. 18, 1956