How about you guys? Coinbase? Exchanges? Wallet?
For holding Bitcoin, there are two main options - doing it by yourself via software or hardware wallet, or keeping it on some online wallet - blockchain.info, exchange or some other service. The first options provides the best safety - as long as you hold private keys you will own coins on both chains and no one will able to force you to use only one of them. The second option is risky, because your funds may be lost due to some network disruptions, wallet provider might decide to support only one chain or just get hacked like it sometimes happen. But there are a few benefits to it - if it was stated before, they will split your coins for you so you won't have to use segwit2x software, and if it's an exchange, you might be able to sell your B2X coins earlier than others.