Where to go?!?! HELPP!

Hi. I’m 16, and this summer I’m pretty sure I’m doing a 6-week summer exchange program. I know I want to go to North America, but I’m not sure what country to go to. I have to have 3 choices, and these are the countries I have to choose from…

Costa Rica

I know my 1st choice is going to be Canada, and I’m not sure about the 2nd or 3rd choice
I was thinking maybe Mexico as a 2nd choice, then Costa Rica or Cuba as 3rd

Can someone who has traveled to these countries give me some advice?
I’m a 16-year-old girl, and I speak a little French (very little)
I want somewhere that I would have fun, and would give me a good experience

Thanks a lot!