I will suggest you coinbase mate. I am user of coinbase since more two years and nothing bad happen never on it. For more with coinbase you will not to pay fees when sending bitcoin because those fees are paid from coinbase. So you save the money of the transactions. Coinbase have millions of users from all over the world and this popularity testify their seriousness and their credibility.
I would not to store a money on the exchanger for long term. someday they will suddenly collapse, remember mt.gox, mintpal.
better to use cold wallet, electrum is my favorite one.