Coinbase is a well known cryptocurrrency exchange in the United States. It is a good solution for someone that wants to trade cryptocurrencies. In the tutorial all the functions needed for trading are presented.
Dash is a cryptocurrency, that has a built-in mixing service, to improve privacy. Since it's creation, it has an increased fee InstantX transaction. With InstantX a transaction is flagged "confirmed", immediately, for over the counter transactions. The transaction's input addresses are blocked till transaction is confirmed by the miners, to avoid double spending. See other posts about trading
Kraken is the top exchange for euro bitcoin traders. The trading platform, which is arguably the best of all the bitcoin exchanges, is number one in terms of BTC/EUR trading volume. Kraken holds the majority of bitcoin offline - cold storage, in other words - with "air gap" isolation from any online network, making hacking theft nearly impossible. See other posts about trading