There are hundreds of Bitcoin exchanges which anyone can sign up for and start buying Bitcoin quickly and effectively. Personally, I use Gemini or Kraken. Gemini has an excellent interface and low fees, while Kraken offers some of the best crypto assets and is one of the oldest exchanges in existence.
The real question is... What is your favorite Bitcoin exchange?
I haven't used Kraken or Gemini at all, so I don't have an idea about those exchange. Although I don't know that they allow or not my country. However, I loved Bittrex but now bitrrex don't have a good position and they are not fair to list a coin. Now I like Kucoin for trading, Kucoin has good live support.