The best place to purchase Bitcoin Cash (BCH) has just opened: https://local.bitcoin.com/
At Local.Bitcoin.com no KYC is required and anyone from just about anywhere in the world is free to open an account and trade BCH for many different payment options or even cash trades in their local currency with anyone they want.
Depending on where you are located, you should be able to purchase Bitcoin Cash (BCH) directly from within the Bitcoin.com wallet by tapping on the "Buy Bitcoin Cash Now" option on the "wallets" homepage.
You can also purchase Bitcoin Cash using any of the exchanges listed at the link below:
Please note that although you can manage both Bitcoin Core (BTC) and Bitcoin Cash (BCH) in your Bitcoin.com wallet, you must not send BTC to a BCH address (or vice-versa).