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?
Talking about trusted exchange I use poloniex and bittrex for my trading work since I was start working as trader fair transaction fees trusted with highly security feature thats why I am comfortable to stay my asset withuot doubt.