Which car should I get as my very first car? I'm looking at a Mini Cooper, Volkswagen Beetle convertible, or a Ford Fiesta

Please let me know! No rude comments please, thank you.

No

Sorry, None of those. The reviews and ratings all say Honda, Mazda, Toyota and Subaru make the best cars. A Mazda 3 or Honda Civic would be great choices.

Try actually asking your parents first.
Since you asking here, indicate you don't have a clue what is required to get a car.
your parents can explain hopefully.
your English teacher can teach you how to write a valid question for wide range of audience also.
NOT a rude answer, just reality that you don't know how to buy a car.

Lol

If it has to be one of these three, then the VW Beetle, its the better quality compared to these other two cars.

The Fiesta is not as unreliable as the Beetle, which is in turn not as unreliable as the Mini Cooper. The Fiesta has some design points - especially the engine temperature management system - that make it a decent choice. The other two… Not so much.