I have BTC (pre-fork) and now BCH(BCC) on a paper wallet. What's the best online wallet to transfer them into to ensure I retain both coins and also to be able to transact with them?
This is copied from the Electrum website today:
Recommendation on how to redeem Bitcoin Cash
July 31st, 2017.
Electrum is a Bitcoin wallet created by Thomas Voegtlin in 2011. Electrum is distributed by Electrum Technologies GmbH, a company registered in Germany, using the website https://electrum.org
Electrum users who are not interested in Bitcoin Cash do not need to worry nor to take any particular action. The following note is only for users who want to access their Bitcoin Cash (BCC).
"Electron Cash" is a fork of Electrum for Bitcoin Cash. Electron Cash is not endorsed by Electrum. It is open source, and binaries (executables files) are available for Windows, OSX and Android. However, when you run binaries instead of source code, you have no guarantee that they match the source code. This is why wallet binaries are usually signed by developers. A digital signature engages the responsability of the person who signs.
The person who distributes the Electron Cash binaries has decided to remain anonymous, and uses the fake name "Jonald Fyookball" in order to sign Electron Cash binaries. Thus, if these binaries contain code that is designed to steal your bitcoins, the author of the theft will be anonymous and walk away safely with your funds.
This danger is exacerbated by the fact that the default behaviour of Electron Cash is to silently copy all your Electrum wallets into its own directory. Thus, if you run Electron Cash on a machine where you previously used Electrum, all your pre-existing wallets will be available in Electron Cash, and you will only need to enter your password in order to expose your bitcoins to potential theft.
Therefore, users who want to run the Electron Cash binaries should do it on a separate machine, that does not have their Bitcoin wallet. We recommend to proceed as follows:
Install Electron Cash on a machine that does not have your Electrum wallets.
Wait until the BCC hard fork has taken place, and a few BCC blocks have been mined.
Move all your Electrum funds to a new Electrum wallet. This will move only your BTC, and not your BCC, because the BCC blockchain has replay protection. Wait until the transaction is confirmed.
Enter the seed of your (now empty) old wallet or private keys in Electron Cash. Since the BTC have been moved to a new wallet, entering your old seed in Electron Cash will not put your BTC funds at risk.
Following these 4 easy steps you will be able to access your BCC without compromising your BTC.