One of easiest way to create and access Ethereum and erc20 token is MEW web interface. My question is , is it safe to keep big amount in MEW or better not to rely on it.
You can safely store your Ethereum and erc20 token in MEW wallet on your mobile. Also if you use desktop/PC, you can store your currency in Meta Mask. Both MEW and Metamask are safe and better than any online exchange wallet because you have full control over the private key.
However, if you have very huge amount of ethereum, than it is preferable to store your crypto in hardware wallets.